Ubuntu has gotten fairly pretentious in it's nature. I remembered it being like one of the best distros to use. I've fallen off from Ubuntu since 11.10 though.

Snaps, Ads, and how many projects they've let go.

Snaps, they are against one of the main tenants of FOSS. Obscure content validation and reduction in free access.

In my personal opinion: 1- Snap packages. Dont like them for their closed source backend, dont lime them for how canonical has been sneaking then into the system of users who have been originally trying to install a deb.

2- Modern Ubuntu simply has no real benefit compared to other Distros. Nowadays it's just another Gnome and Debian-based distro, I see no reason to use it over Debian itself, or Fedora, Solus, or any other Ubuntu derivative that simply does better than "vanilla" Ubuntu, such as Pop!_OS or Linux Mint.

I don't hate Ubuntu, and I recognize it's importance for Linux as a desktop in it's early days, but Canonical really lost track of themselves.

The general philosophy behind it.
Ubuntu started out as Debian with some improvements.
Once they were established as the primary Linux distro, they pivoted to an MS-like approach. They tried to invent and implement their own solutions for things that an agreed-upon solution already existed, and was in need of manpower to iron out the kinks (best example is developing Mir instead of throwing their weight behind Wayland, or creating Unity instead of improving Gnome).
They also tried again and again to monetize their OS, which they built on top of millions of volunteer work hours from the Debian project.

All of these efforts failed so far. Their current "we can do it better" project is Snaps, which again duplicates volunteer work instead of contributing to Flatpak which was there before.
I'm willing to admit this one does make sense, since their goal is to make an OS where everything except the kernel and the init system is a snap, something which you can't do with flatpak.
But I'm also pretty sure that'll fail again.

If they simply built an OS with a Debian base, newer packages, 2 releases per year, an LTS every 2 years, and a GUI selector for Gnome or KDE in the installer, they'd be the perfect beginner distro. On the other hand, then they wouldn't make any money.

For me, Snaps are the thing. Ubuntu has chosen to use Snaps even for things readily available on other distros / in many repos without the need for Snap.

Linux is about choice, and making that kind of decision eliminates some choice. And given that Ubuntu is commonly recommended for new users -- partly because it is often one of the few distros with official support for stuff -- it's extra annoying.

Edit: in practice, there are many Ubuntu-like distros that are probably just as good for new users and don't need the Snaps (e.g. Mint). But new users won't know this. If Ubuntu were not the behemoth it is in terms of name recognition, many people would care less.

Canonical, the owners of Ubuntu, love to steal open source projects. They'll help a project with development power, then force the contributors to sign a CLA (for an example see the fork of LXD called Incus). Canonical also uses and forces proprietary systems onto the user's, e.g. Snap uses the proprietary and hardcoded Canonical repository, which Ubuntu now defaults to using Snap for installing packages.

Side note, if it wasnt for Snap using a proprietary backend and also depending on AppArmor (generally regarded as a weaker MAC than SELinux), I would prefer Snap over Flatpak. It creates a better sandbox (aka the actually Security of the software), avoids sandbox escapes, blacklists against broad permissions (e.g. $HOME access), and Snap packages generally have stricter permissions (which determines the real-world security of Snap). Sandboxing is very important for Desktop (and server) security. Android is does the best job of this, but it would be nice if projects like Sydbox, Crablock, or Bubblejail were adopted and built-in to the package manager.

But even without any of the previously mentioned problems, I just think Fedora is a better OS. Fedora comes preconfigured with SELinux policies to confine system services they are quicker to adopt new technologies. Fedora is also a semi-rolling distro, meaning packages are quicker to get updated than on Ubuntu. Fedora stays FOSS, where as Ubuntu becomes more locked down. Also, the package Brace made by the developer of DivestOS is great for quickly hardening a Fedora system.

to me none!! i like ubuntu a lot and specially xubuntu

Snaps and how they tried to ram it down my throat with firefox lol. Pure shit

It's a corporate distro whose company's actions are against the linux philosophy.

Corporate ownership, but you can have that and still be generally accepted in the community. Like both Fedora when controlled by Red Hat and Suse when controlled by Novell.
One of the real problem is their dual license policy for their open source projects, that grant Ubuntu full license and the power to close in an Open source Project if they want. This is decidedly against the GPL spirit, but can be done with dual licensing.
Another problem is the "not made here" mentality, which undermined Wayland for instance.
Ultimately the problem is I guess, that Ubuntu is (was?) trying to make Ubuntu exclusive to Linux, with Canonical controlling key technologies. Seemingly an effort to reduce other Linux distros to second rate players.
Another example of that (apart from dual license and Mir) is their new package system Snap, which is open source on the client side, but proprietary on the server side.
Obviously it's not a good idea for Linux to use proprietary package systems.

These are of course ideological issues, if you don't give a shit about those, I suppose Ubuntu is mostly OK. Except minor annoyances like media not working out of the box. And that the PPA system sucks.

Snap. :)

I'll give some anecdotes.

1. A friend long ago was setting up VSCode and Java. He wasn't the most familiar with Ubuntu, or Linux at all -- imagine his struggle when his JDK couldn't be found. Why? Non-obvious to him, it was sandboxed as a snap.
2. When I was a noob, I was looking for a package for some app, but when I found a PPA, it was an enormous command to set up. And hunting online for software... how Windowsy.
3. When I was a noob, I was theming my system with a mildly rare theme. But Firefox was a snap. And since the theme didn't have a snap, I had to try to integrate it myself or de-snap Firefox... shiver

Maybe it's changed now. But (1) pushed me to Mint, (2) pushed me further to distros with simpler text-based package management, and (3) is hopefully easier nowadays.

Bottom line (as many agree): Snaps are uncomfortable for a lot of levels of Linux.

Most of the criticism I have seen online stems from how Canonical (the company behind Ubuntu) plays fast and loose with the FLOSS ethos. The earliest controversy I can recall was the inclusion of the ‘Amazon shopping lens’ in its Unity desktop environment. There may have been earlier issues, but this one made mainstream headlines in the early 2010s. More recently, the push for Snap (its application bundle format), which relies on proprietary server-side components, which invited criticism.

That said, I still find the OS ideal for most users. It has been (and still is) a gateway OS for many Windows and macOS refugees, thanks to its strong community. It was for me nearly two decades ago, and I prefer to remember Ubuntu for the good it has done for the community.

Ubuntu is like all other Linux distributions, they add to fragmentation.

Everyone should run Arch Linux

I use arch linux btw

Here we go again... Some historical reasons, and some technical. Here are a few (strong points) that comes to my mind:

Ubuntu has a track record to do their own thing and splitting community or the entire Linux eco system, such as with Unity, Mir and Snaps. Unity was badly implemented desktop environment in the beginning and lot of people didn't like it. Although I think it was a great DE over time, it was just another fuel in the fire. More serious problem was Mir. Mir was an alternative to Wayland, because Canonical was not happy with Wayland and they didn't want to implement what Ubuntu tried to do on phones. But that meant the programs and protocols to support was now X11, Wayland and Mir. And related to it, the focus of mobile user interface on desktop (Mir+Unity) was something lot of desktop fans didn't like at that time. Canonical gave up on Mir and Unity (and smartphones entirely).

Snaps were very slow at the beginning, some people does not like that it fills the device loops, and not many apps were available as snaps. Snap is a similar but alternative technology to Flatpak. Again, because Canonical was not happy with Flatpak and Snap truly has some advantages over it. But it means splitting the eco system once again. But what made it really upsetting for many is, that not only Snap is pushed by Canonical a lot, but also when installing a native package, the package manager would silently install the snap version instead. That is sneaky. And not only that. The Snap repository from Canonical is proprietary. And if you want support Snap, you have to use that repo or use your own repo. Unlike Flatpak, you cannot have multiple repositories. That means in Snap you can only use Canonicals proprietary Snap repository, because otherwise you would not have all the apps in it.

There was some Amazon related datas send to Amazon with an app, every time you searched in the search bar of Unity. Even though this is gone for long time, it still is something people (me included) remember. Some say it was spyware... which is kind of was, but is up to debate.

Also some do not like that Canonical is a corporation. I personally don't have a problem with that (and used it for 13 years exclusively), but its something to mention what problems have with. Also Ubuntu is used in Windows too, so people have conspiracies too or do not like their cooperation. I'm fine with that and actually like that Linux gets more exposure this way. But again, some people don't like it.

You spend a lot of time fighting snaps. I wanted to install GrapheneOS which needs direct access to USB from the browser. Snaps can't do that, so I had to hunt for a chromium .deb on the web. Might as well use windows if I'm doing to Google "$software installer"

I use Ubuntu every day. I'm part of the Linux community. And i believe that Ubuntu helped to make the Linux desktop easy and available and sort-of cool.

There's no hate, but i could live without snap, unity and oversimplification. Actually that's my biggest issue. Give me settings, give me choice. Hibernate works fine on my machine, don't hide it.

Apt/deb is a fine package manager, flatpak and docker can supplement it when you want something not packaged as deb. The way Ubuntu updates browser over snap is a small improvement, but it's not worth deviating from the rest of the Linux world.

I don't hate Ubuntu. I think they are wasting their time on stuff no one needs. Missing the chance to improve Linux for everyone.

There's nothing bad about Ubuntu, but Canonical rips a fat line and says, "I'm going to make my own display server, with black jack, and hookers!" Which isn't necessarily a bad thing, innovation is good and all, but they release a steaming pile of crap that doesn't really integrate well into the rest of the Linux ecosystem. They spend years telling everyone that their display server is the best thing ever and no they won't offer any alternatives or integrate it into any of your systems thank you very much.

Then 10 years later they unceremoniously dump it in favor for whatever everyone else has been using.

I just wish they would funnel all that innovation upstream instead so everyone benefitted instead of just Canonicals bottom line.

Ubuntu initially positioned itself as a staunch advocate for free software, reflecting its roots in the principles of open-source freedom and collaboration. This ethos is captured in early mission statements and community declarations that emphasized the "freedom to use, share, study, and improve" software.

Today, Ubuntu still mentions its commitment to free software, as noted on the Ubuntu Community Mission page, which emphasizes building tools accessible to all and maintaining an ethos of openness and collaboration. However, its approach has evolved to include a pragmatic balance between free software and proprietary solutions.

Snap is the biggest issue.

The developers say they are awesome and the fans say they are awesome.

It doesn't change the fact that they kinda suck, the forced updates kinda suck, and the tone-deafness of the fans kinda sucks.