Much too early to say, all we've heard about it are rumours. You ask me, microsoft want to hurry up and say something about it if they do have plans for the "nextbox" as we're calling it now. None of these rumours have been exactly good. Always on DRM, no backwards compatibility, so on.
What I want from it, though, would be a much larger standard hard drive, for one thing. I don't believe completely digital gaming to be the future, at least not the near future, download speeds need to be more consistantly good before people can start downloading whopping 8 GB+ games with little trouble, but it is, no doubt, becoming a big part of gaming, and I don't want to struggle for space like I have this gen.
Furthermore, I'm actually hoping the disk drive, and the backwards compatibility, is still there. And none of this "some games work, some games don't" BS either.
I'd also hope for a better UI, it's appalling that after so many updates, the xbox live marketplace can still be so annoying to navigate, taking an age to load up stuff like a particular game page, search result, and especially when you want to look at screenshots, which I swear to god sometimes don't come up at all.
Finally, no focus on bloody kinect. Come back to that one when the technology works precisely, microsoft, and without requiring practically a fucking warehouse to play with up to four people.