Windows 8 on the whole feels a bit disjointed with the metro interface being completely separate from the classic desktop. For instance, I installed it on my netbook with a screen resolution of 1024x600, which is too small for metro apps to run. The internet explorer tile wouldn't open because of this, but when I opened IE via the desktop, it ran fine (I only used IE because I hadn't yet installed a better browser).
What bothers me the most is that the interface is also very tricky to navigate using a mouse (and even more so with a touch pad) since users are expected to navigate it in exactly the same way as touch screen users. This results in many unnecessary movements across the screen which requires more effort to open the desktop, for example. Also, there are many options and buttons which are hidden on the screen, which is great for smaller tablet screens, but causes further unnecessary mouse movements on larger desktop screens.
I don't know what it is, but the whole feel of Windows 8 doesn't make me want to upgrade from Windows 7, which is a pity because there are some great new features (such as being able to pause file transfers). I think it will work great for tablets, but I really wish they didn't copy+paste the same OS to desktop users. At least it is some consolation that there are very few core changes from Windows 7 (save for the metro interface, course).