I like it, but, there are upsides and downsides.

I usually play with a team that has some remote members, so Foundry is the mechanism by which I create shared visuals and battlemaps. I don't go as far as to run the whole game with Foundry -- PCs have their character sheets, they make their rolls themselves, and I still track most elements of the game myself (except initiative-order and NPC/monster HP).

Even with just this light usage, there are downsides -- for example, my prep as a DM takes longer because I have to create or adapt a map/visual for everything, as opposed to just describing it. I'm preparing an adventure right now that I might be done with if I didn't use Foundry; it's all documented, but not visualized.

Many (for example, the linked article) add more capabilities to Foundry until it runs and automates more and more of the game. I think I'm concerned about creating a slippery slope with that, to the point where we're playing a multiplayer video game rather than an TTRPG, and the flexibility of the game is lost. But!, I add a thing here or there, trying to make my players' experience better, and so far it's all been great.