As we use Media Center - the following were issues with 7 at this stage:
* EIT data for EPG (over the air rubbish instead of 2+ weeks worth from EPGStream)
* Bluray playback - Play Movie just is not compatible with 7's Media Center.
* Media Center remote - very laggy and sometimes non-responsive. Also skip back/forward buttons on remote were non functional. According to reports on other forums, I'm not the only once experiencing this.
One thing I do like is the music player section of Media Center in 7. It constantly moves the album art and text around to help prevent burn-in. But the nice part about it is the constantly scrolling wallpaper of all your album art. Very pretty.
I fully intend to re-evaluate once Play Movie is updated to suit 7. EPGStream has a WIP for their guide data.