They are only as fragile as your type source.

Maybe not 'fragile' as in buggy, not buggy, but I found them to be 'quirky'. Sometimes stop working unless I close /re-open VScode. Stuff like that.

And other downfall. Do they still not work with DOTNET Core??

They've worked for several years now on dotnet, but the type provider author has to do some work to allow their type provider to compile and target that runtime.

Yep, implementing one (a solid one) is hardcore. But think about it. Building, say, an XML or SQL type provider is a big deal. Doing it right requires special talent, because you are essentially building a transpiler to seamlessly interface with F#.

But this is also it’s greatest strength. Having direct, type-safe access to structured data is truly awesome. What else compares? Certainly not conventional code gen.

Oh, don't get me wrong: Type providers are absolutely fantastic. Just, they are such a complex beast, most implementations I used so far are pretty fragile, at best. But tbh, even a fragile one is surprisingly useful