I've donated a few cents to them here or there, but really nothing very substantial (not that they deserve anything substantial).
they definitely suck and I didn't really want much to do with them from the time I was bidding, knowing their success rate seemed precariously low already. the problem is, most lenders had them as their Default at the time and either didn't think much or bother to change it, or even know how. this I found greatly unfortunate, and made a thread on the Prosper forum about it.