Wow, I can't believe nobody commented on the lack of Ads.
People cried and moaned all this gen about the Ads on the 360 UI. Well this vid shows a serious lack of ads. I'm sure there could be ads within the marketplace ui, but it looks like MS moved them out of the main screen completely.
That's a big win in my book.
As far as the look, the start screen looks fine, with your game getting the big tile treatment. The screen to the left with all of the smaller tiles looks rough mainly because its a bunch of green tiles. If this is the same beta software we heard about before, then it seems like they are still working on it and that means time to clean up that wall of green tiles.
The most recent articles on the updated UI shown behind close doors made no mention of an ugly ui or an issue with a wall of tiles, so maybe they have already changed it for the better.
For me, the only thing I think doesn't look nice is that left side wall of green tiles, so if they clean that up, I'm happy. The performance looks great.