I have noticed a trend. There are several engineering software packages that I use that simply will not run under Windows 8. The vendors have basically said use Windows 7 (or even XP) or move to Linux. This obviously does not affect most users, but it is interesting.
I have used the UI for Windows 8 for a couple of years now. It works, but I do not like it. I think it is rather poorly designed.
So other than the fact that it will not run the programs I need and I do not like the UI, I guess it is a pretty good operating system.