Holy crap. Winamp5 is *outstanding*.
I, and friends of mine, had recently switched to iTunes because of the ability to create "smart playlists", or playlists that fulfill certain search conditions. Winamp5 steps an entire level above iTunes' ability and adds SQL style querying. This is especially useful for people with a large number of MP3 collections, and makes a large collection far more manageable, and enjoyable.
Furthermore, Winamp's stability is far greater than iTunes in Windows, as my computer slowed to a crawl b/c of the terrible memory/cpu leaks in iTunes, which I have not yet (and don't expect to) experience in Winamp5.
My hats off to Nullsoft. Thank you for making my music experience more enjoyable.
-Ankur