I think it would be great, if they would polish the core libraries.

Too many subtle differences when I've tried it the last time (some years ago). Afterwards we changed our course and stopped using it.

We were mostly interested in using Winforms applications on Windows and Linux - but it didn't really work for our application. I had the feeling that Xamarin wasn't interested in making the code any better for our use - instead they were interested in mobile application development.

If Microsoft baught them I really wished our use case would be improved too.