I have no practical usage with the new operating system, however the general consensus is that underneath the Metro interface, it's a faster, smoother version of Windows 7.
I happen to love Windows 7 for the mere fact that the OS feels like it's not even there. I don't want to spend loads of time maintaining the system. I want to spend loads of time using applications on the system.
The only pitfall that I think Windows 8 will run into is that it was released way too soon. Many businesses are still upgrading to Windows 7 to this day, and Win 7 is going nowhere anytime soon.
So whether you upgrade or not, I think you will be happy with either choice. Given that if you don't upgrade then you're probably just as happy with Windows 7 and that is ok too.
Windows 8 is a necessary stepping-stone for the future of Operating Systems. There are other OS's looming that are both more mobile and user friendly (Android, I'm talking to you.) And more powerful (Linux, I'm gazing in your direction).
Personally, I'm buying a laptop with Windows 8 preloaded on it. Lets see how it goes!