Here's a pretty detailed blog post I wrote about it.
Organize, Track and Cloak Affiliate Links EASY - GoTryTHIS
HOWEVER I don't really use it for affiliate links as I don't really have time to do much affiliate marketing. I use it for tracking my client links so I can track outbound clicks. So do research to be sure it's still a good option for affiliate links. I think it won product of the year in 06 or something so I think it’s pretty good.