I've been playing with the new version of iTunes for the past hour or two and the first thing that strikes me is all those annoying little arrows that link to the music store. I could perhaps see this being useful every once in a while, if I think to myself "I wonder if there's a new record by Mountain Goats?" but I can't see doing that more than once or twice a month. Why not put a "Look up in the iTunes Music Store" right-click menu option instead? The weirdest part is that my own purchased music has links to the store... so I can purchase them again? I'm turning that off asap but I still wonder why the arrows are turned on by default. Perhaps, as Tom just told me, to blur the lines between "your music" and "the store music for sale" which would certainly increase sales.
The party mix is weird looking, interface-wise, I wonder if it's using any sort of BPM analysis to arrange songs next to each other. I can't really tell the difference between that and random shuffle at this point.
Andre pointed out compilations to me, which I didn't notice before either. It appears that they're reading compilation info from ID3 tags now, and putting albums by various artists in the Artists browse list, which is kinda useful.