At the moment, iTunes feels kind of bolted together. It started off as a music app, and now it's the hub for a whole bunch of things movies and TV shows, music vidoes, ringtones, that sort of thing. It works and works quite well, but it doesn't feel like it was properly constructed around it in the oh-so Apple way we all know and love. All it needs is someone to sit down with a notepad and a pen and rethink everything from the bottom up and it would be a whole lot better, even if it was just reorganised in a minor way. Movie playback, for example, is functional but isn't as spiffy as it could be it's a lot nicer to browse through your movies on an Apple TV, and while this interface is well suited to a fullscreen setup a similar vibe needs to be applied to iTunes 8.
The other pretty minor request I have is for artwork to be gettable for movies. A lot of us OCD types out there prefer the iTunes artwork, but for whatever reason we can't get it. Following on from this, iTunes can be a total pain in the behind when it inexplicably refuses to give you the artwork even when the tags are identical. There should be a way, if you're logged into the iTunes Store, to just hit a button and get access to the artwork for situations like this.
Oh, and please please pleaseeee moves music videos back to their own category? It drives me loopy when I'm shuffling music and I get stuck inside a surprise video.