I'm a bit of a fan of Media Centre Edition too, and so far my (albeit limited) experiences of MCE on Vista have been OK.
The really frustrating thing is that MCE does not support DAB Digital Radio, which is incredibly annoying. Microsoft UK keep making platitudinous noises, but nothing has come out of it yet.
I'm rather hoping that some of the USB DAB receivers (MTech and so on) willl get some MCE compatible drivers, and make it look like a Video Tuner source, so you can tune into the DAB, see the DAB visuals and get the EPG data into MCE. But it hasn't happened yet.