My love affair with my new Mac continues, but there are a few things that are a bit irritating. iTunes insists on running a process called "Determining Gapless Playback Information" - this process looks at all the albums in your collection and with some algorithm allows you to play them back with no crossfade gap. Good in theory, but bad if you have a 250 GB music collection on a shared network drive. There is no way to turn this feature off, and it basically renders iTunes completely useless while it runs.
It will probably take 2 days to chug through my collection, and once finished; since I don't rip entire albums for the most part, it probably won't have much effect.
I also have all the album art for my collection, but iTunes seems bent on downloading it again, I can't seem to get it to 'see' that it already exists.
I think there are some ways to tinker with your iTunes folder, but I haven't figured out quite everything.