I've been using Poisoned the entire time I've had a Mac, and I find that while it works some of the time, it doesn't yield many results, is relatively slow, and doesn't handle corrupt downloads well at all.
When I need stuff on Gnutella I use Acqlite, wouldn't recommend LimeWire mind, never used that. But when people send me stuff I usually prefer they use bittorrent instead.
I used to use Poisoned but its not as friendly as Acqlite. Both are unreliable in my opinion. However, I have both installed as other people on my computer prefer it. Acquisition is the best looking though, just don't use XFactor (It's metal! )