I'm looking forward to using the new Windows. No, seriously. This is probably the biggest change Microsoft has made since 3.11. The concept of a Metro interface with multiple jumping off points, and without hierarchy of content, resonates with the way I use my machine, and I admire MS for thinking beyond a desktop workflow that has remained more or less the same for over twenty years.
Of course, the devil's in the detail, and MS has a bad habit of taking good ideas and screwing up the execution (see Vista, which is basically Win 7 on its head). I'm also a bit wary of this concept that Win8 is necessary in a world where mobile and desktop are merging - the so called 'responsive design' philosophy, where the same apps morph and flex to be used on all kinds of devices. As a UX person, I've seen this concept fall over time and time again on the web, because oftentimes the mobile and desktop use cases are too radically different to be met by a single interface. Still, I'm keeping an open mind and looking forward to playing with the new OS.