I haven't really checked out any of the RP comms, so I don't know what RP is like there on the whole. As a site, IJ is clunkier than LJ (slowdowns, for instance, that they've mostly fixed but might come back); the down side of being smaller and less businessy than LJ is that they don't have LJ's resources. And the "Insanity" schtick still really gets on my nerves. On the other hand, 100 free icons! Ant the guy who runs it gives numerous updates on the front page.