Crackdown is all it's meant to be and more.
The Good- The gameplay is fun. It's unique as well. Jump from rooftop to rooftop and shoot at all the bad guys scurrying below. The explosions aren't half bad and the physics engine is about as good as it gets in a game such as this.
The Bad- Although there seems to be more bad then good, the good still greatly outweighs the bad. The graphics aren't super good. You're not playing with x's and o's but you're also not playing with modern day high-tech models. The screenshots show a pretty accurate depiction of the graphics. They're not enhanced via photoshop or anything to make the game look great. The game DOES get a little bit repetitive after a while and will eventually wear off. But what game doesn't? I find my self spending lots of time scaling my way of buildings multiple times through game. To some, that may seem fun. For me, if I wanted to scale up buildings I'd go and get a copy of spider man where I don't have to worry about if I'm going to make it or not.
It's one of those games that pulls you through to the end and then sits on your shelf for like 6 months then you suddenly have this overwhelming urge to do it again. For what it's selling for now-a-days, I'd say it's definitely worth it. I got my copy for $10. So if you're one to like GTA 4, or Saints Row 2, I'd consider this title. It's not too old but it's not new either. You have an open ended world in which you go around and take down key leaders of gangs and blah blah blah. A stereotypical gang fighter. Yet with a new twist and fun gameplay.
All-in-all, it's fun, unique, and it's worth giving a try.