It's a blast, some interesting ideas but the game lacks depth in many areas, pick up and play for a while, it's fun
I'm a fan of the GTA series and I also enjoyed Saints Row but the "agent" you play in crackdown has some great powers that make this style of open city game a lot of fun. You can jump 30ft into the air, survive massive falls, leap out of the water, kick cars over, throw cars at the enemies face and cause huge amounts of destruction. The agent feels powerful and I should imagine it'll be a bit dissapointing when I play GTA 4 when I cant leap into the air like in crackdown. Seriously if you've never checked this game out it's at least worth downloading the demo from XBL just to have a go.
The game play is almost one dimensional, KIll gang bosses, the story is very thin, clean up the city this is the mojor drawback. This title has nothing like the nuances you'd expect to find in a GTA game, please excuse the repeated comparison but it's difficult not to mention GTA when discussing crackdown.
The end result is that crackdown is fun to play for a while, it doesnt offer you much immersion into the game world but if you want a good low stress game where you feel ridiculously powerful then check it out, especially at the current price.