Two people I know have now been burnt by iTunes / iPods and their policy of restricting access to data they own. In both cases, they've suffered a disk failure and have been unable to get their songs back off the iPod. They were both under the mistaken impression that their iPod was effectively a backup of their song library. A reasonable position to take, I would've thought. My MP3 player can be treated as such a device - why can't an iPod? But they can't copy their music back off the iPod into iTunes.
More recently I've suffered an annoyance at the hands of iTunes. It turns out that when you edit song meta-data iTunes doesn't edit the ID3 tags in the actual MP3 files. When I copy the MP3 files to my other computers and devices, the songs have none of the track/album information that I entered for them. These are freely-available tracks, by the way. I'm not breaking any copyright in copying them around.
So, what can I replace iTunes with on OSX? Something that supports Ogg files out of the box would be nice too. If only Amarok worked...