After years of letting iTunes do whatever it wanted with my music, I'm very happy to be back in control with MC.
I switched to iTunes because of Apple hardware - macbooks and iphones - but with a large (40,000 song) collection, combined with my geeky collector's scrutiny, iTunes just didn't cut it. It just doesn't have the organizational muscle that is required to get a handle on a large collection.
Pulling my music back into MC I found that iTunes had made a mess of some of the finer details - cover art was different from track to track, a few tracks were mysteriously missing from albums, file naming wasn't always the same.
I'm also absolutely delighted to have user-defined library fields back.
I am running MC through VMWare's virtualization software, but can't wait for the native OSX app.
That's all. I'm happy to be back.