There are many great features of iTunes. The query implementation, including the ability to nest queries, is superb.
Against this must be set the fact that iTunes is not a Mac application. If it were produced by anyone but Apple we'd all dump on it.
iTunes does not respect the Dock, for heavens sake! It ignores it when sizing windows. Even Firefox 3 respects the Dock (a very nice improvement over FF 2 in that regard, among many others).
Click the green plus icon on any Mac app and the primary window sizes to the "largest size consistent with good screen practices". Click it on iTunes/OS X and you get the mini-player.
That's just gross.
Firefox 3 is a vastly better OS X citizen than iTunes.
Isn't there anyone in Cupertino with a modicum of shame?