I always hated the idea of Saints Row, because of the gang theme, and the whole 'GTA rip off' vibe 9seriously, why would you rip that off? It sucks.) But for some reason I picked up SR3 and for me, it was probably the most fun game I played last year. I mean like pure fun value. It isn't serious in any way, its not highbrow, its not trying to be art, its just balls to the walls fun
Also, I got it on PS3, so got SR2 for free!
Now don't get me wrong, SR2 is bigger, and there is a hell of a lot more stuff to do, but after playing 3, it feels like a step backwards. The controls are clunkier, the graphics aren't as good (though it does look slightly more 'real' that SR3, or maybe thats because I spent most of that game running round as a blue haired anime chick with titanic boobs and a clothes alergy) and... I dunno. Like i say, its not a bad game, far from it, better than I expected, but definately one to play before SR3.
As for similar games, well, there aren;t really many other zany games like this. Just cause 2, sure, but other than that..?