Well I'm trying out the RTM now. I tried to remain hopeful but I'm pretty disappointed.
As I'm playing with it I realize more and more how metro makes no sense for a desktop. I originally envisioned Metro as a fullscreen replacement for the Start Menu. Stupid but livable. It really is more than that. It is two separate unavoidable UIs in a single program and I can't think of any example where that was a good idea. The switch from the fullscreen metro UI to the desktop UI feels jarring because they're so different. Its not clear when you'll get one or the other. For example, when you open Internet Explore from Metro you get metrofied IE. But if you pin that same Icon to the task bar and open it there you get desktop IE which is unconnected from the other(different tabs etc.)
I have no use for giant full screen apps on a 24" monitor. For example, Skydrive pops up with ridiculously huge in your face icons and rudimentary things like drag and drop or no longer possible. Or messenging, do I really need a full 24" screen to send or receive an Instant Message. Furthermore, applications like newegg, bing, Wikipedia, etc. are pointless on a desktop. On a tablet the applications can be better designed for touch interfaces. But on a desktop the website is already the desktop UI.
The desktop itself isn't all too bad. It's just a slight evolution on windows 7. Things like explorer and task manager are nicely improved. Its pretty clear that not a whole lot of effort was put into it compared to metro.
These are only my opinions of Windows 8 as a desktop operating system. You can argue that desktops are fading with the rise of tablets. but that doesn't mean a tablet OS makes any sense for those of us still using one. I don't know why Microsoft wants to sell it to us as the successor to Windows 7 and not as Windows Tablet 8.