A fun world to mess about in.
I found the need for the "Respect" meter to be filled an interesting deterent to just blazing through the games missions, though that is quite time consuming. Perhaps I'm not a great player, but some missions have taken me _many_ retries, to the point where it's "forget chasing this guy down... how do I get me an RPG?" (which works, btw, dead is dead, and you can just buy the darn RPG at the local weapons concern). Regarldess Respect is a great incentive to go out and drive som hos around, steal some cars, or make some hits.
The ability to customize things is really emphasized in Saints Row but I found myself not too concerned with it after pimping out myself to a degree and then doing up a few cars, I lost interest. But if that's your thing there's a whole lotta flexibility here! Huge selections of clothes, bling, a plastic surgeon to rearrange your face and wick chopshops with enormous amounts of customization available for cars.
Aside from the music one of my only gripes is the lack of personality of the main character. I think the silent route was the wrong one; one of the things that makes GTAs great is that the main character is usually well voice acted (Ray Liotta was pure genius!). The main dude being mute just makes him a pure avatar absolutely devoid of any personality other than your own destructive nature. All the other characters are well acted.