Well, I've used
eXeem for a whole 2 days now. It is currently in public beta version 0.20
Pros:
Easy to use search function
Semi-large library of files (13313 files, ~6+ TB data)
Built on Bit-Torrent style systems
Cons:
Resource hog (~17 megs of RAM while idling, maxes processor speed when not idling)
Not enough bandwidth/file (not enough peers); slow downloads (~1 KB/s for rarer files)
A large number of crash bugs
It might turn into something beautiful one day. But right now it has a lot wrong with it.