Here is a statement on the frostwire website on why it was made and why its so similar to limewire. HERE
Basiacly frostwire is almost the same code a limewire, however, it is being run but ppl other than Limewire LLC which might be filtering out illegal content (pretty much everything). I have yet to run into any problems finding a specific file with it. Also, it uses the same exact Gnutella network that limewire uses and most other p2p programs, so no matter what program you end up using you are gonna end up getting pretty much the same results. I can say that I personally use it daily and love it and so do about 30-40 other ppl that I have told about it. Everone seemed to start having problems with limewire not connecting, installing correctly, and whatnot so this is a good alternative. If you dont like frostwire Kceasy looks pretty good too. I might have to check that out to see what all it is like.