It definitely has its warts. I've been making a game using it and I've been annoyed how difficult certain things have been. 3D and cross-platform support in general isn't great (it's technically there, but any platform outside of Windows has a lot of hoops to jump through, at least in my experience).
But it's also one of the more lightweight and code-centric game development frameworks out there currently, and I do prefer that to working with a heavy bloated editor like Unity (which I've used professionally in the past). And as long as my game takes the warts into consideration, 95% or more of my time is just spent coding, not figuring things out the quirks of the framework or engine.
Like I had some issues getting some animations to import properly from Blender the other day (there's some video with like 100 views of someone who got something a bit different sort of kind of working, but I didn't feel like figuring out how to decode what they're doing and transpile that over to my needs), and just decided "Okay, I guess I'm not going to bother with making animations in Blender and only use static models instead. What I wanted it for isn't really that necessary anyway." And I'm only targeting Windows for now. I'll try to get other platforms working later, if ever (got it working on Steamdeck, at least).
It was also pretty disheartening to see almost zero development on Monogame over the past year (judging by its Github activity).
I have been considering giving Godot or Defold a try for my next game (Godot I was highly considering since it has XR support, and I've really wanted to make a VR-compatible game for a while now), but I'm hoping I can at some point jump back into Monogame once this Foundation gets into gear.