I finally decided to pick this one up for its full price. So far, I'm having quite a bit of fun, and thanks to trophy support, I should be able to get a decent amount of play time through it. The controls take a bit getting used to, but once you get the hang of it, it's pretty easy to switch back and forth between characters and stuff. I'm wondering how the game plays in coop though. I'll have to see if any of my friends are interested in some gaming some time.
One thing that bugs me though is that there isn't a background graphic for the game in the XMB (though there is music), there isn't any Dolby Digital support in game, and there are no trophy graphics. I'm nitpicking, but when $4.99 games on PSN have all of these things, it's a little disappointing to see a $20 PSN title be half baked on its presentation front.
That said, I did a little digging and apparently in the EU, a patch remedied these problems. The developers are waiting for the patch to be applied in the North American version of the game by SCEA.