It was supposed to be great. Instead it just combined Kazaa and Bit Torrent, but instead of being better than both, it just kinda ... sucked.
It's not terrible. It's not great. It's just... boring. Not a lot of stuff on the network, either, since people are pretty paranoid about its lack of privacy features.
Add to that the fact that it had spyware for a while... and, well... shrug