I already knew about the custom tags because I used iTunes as an mp3 player on my PC for a while. Later, when my music folder grew larger, iTunes started performing like crap. Even when no other apps were competing for resources, it would stutter on playback. iTunes didn\'t like LARGE mp3 files, such as high fixed bitrate files. It seems to be optimized for Apple\'s proprietary standard, which is no surprise.
I do like the coverart feature, and I wish my iRiver supported it because it has a color display. However, I never used the preset EQ, song ratings, etc.