I'm using the Windows 8 CP on both my home desktop and my Samsung Series 7 Slate.As an operating system, it's pretty solid and the keyboard/mouse combination works very well for me, but then again I've been using PC's since the days when they came with CP/M as well as DOS.
The apps that are available, or should I say 'App Previews' are the weak link. Very few of them are actually functional enough to use properly. The only Metro app that I use regular is IE10.
From a development stand point, I've built a few prototype applications and have done since the original developer preview. It is a frustrating experience, given the lack of any real decent samples or of any developer documentation. WinRT/XAML is just different enough from WPF/XAML to be incredibly frustrating. Trying to work out which of the new controls is best for certain types of UX and what properties you actually need to set is very annoying. Couple that with the rather bland Visual Studio 11, it's not always a lot of fun to write code on Windows 8.
The lack of support for things like Xbox Live and other apps in the UK is also annoying. Not giving me a chance to give it a real; consumer test. I'm hoping to see more frequent app updates over the next month or so.
The OS itself works and does the job well, it's just the applications currently available that leave a bad taste in my mouth.