I use KaZaA and it is fairly straightforward to use. It also cross-searches into MusicCity when looking for downloads.
The major problem with KaZaA (though they would call it a feature) is that if it finds multiple users with the same file (size, bitrate, etc, etc) and you have available downstream bandwidth, it will try to split the download across the users. The problem is occasionally you will have 2 people that ripped the same using the same settings except, for example, one used normalization on the encoding. The result is the recording level of the song will start changing as you hit the different sections of the file downloaded from the different persons.
Of course, KaZaA is spyware (meaning they have compiled in a third party advertising library), and it also is supposed to limit MP3s to a bitrate of 128 or less.