I didn't have to switch because I've never used a smartphone to begin with. My current dumbphone has a great UI, touchscreen for easy input even though it's a very small screen, headphone jack, SD card slot, etc. It can act as a hotspot and has maps/voice navigation and current weather + daily forecast. The Tello service plan I have (uses T-Mobile network) is about $9.40/month. That's with 1 GB data, but you can get unlimited data if for some reason you want that.

There is also a subscription available ($3.50/mo) which gives you live updated maps, voice dictation, and hourly weather+radar but I haven't needed those things (edit: though I'd like to have the radar). I just use the offline maps (more private anyway--you periodically download the latest map data), and I don't need the other stuff. (edit: I have a Sunbeam Wireless phone and live in the US).

There are some inconveniences of course, like all the businesses you interact with want you to install their tracking apps, but I wouldn't put that kind of crap on it even if I did have a smartphone. The main one that causes me issues is the grocery store that has special discounts ("digital coupons") on some items if you use their app. I already have their damn store card which gives me the sale price on most stuff but now they also have this digital deal crap. I can work around that by going to their website ahead of time and look at what all digital coupons they have that week, and click on the ones I want so they will be on my card, which gives me the discount at checkout without needing their app--but I strongly resent having to do that. If they want to put something on sale, put it on sale for everyone! But no--it's all about tracking you. Pigs. But I digress. Point is I get by fine without a smartphone, ymmv.