Initial impressions:
The game is pretty awesome. Climbing, platforming, ranged and close combat, that all feels great, and the mission I completed so far felt like a real mission, which is odd for a sandbox game. The comic book villain look (and behavior) of the enemies helps quite a bit.
The graphics are a mixed bag; Cole moves well, other characters look good, and the city has a lot of detail. At the same time, it feels cluttered, and the high level of detail really makes the aliasing stand out. On the other hand, the detail makes sense, since you can interact with so much in the environment. Including blowing shit up.
This might sound stupid, but as far as gameplay mechanics go, I don't think that comparing it to a blend of the best of Crackdown and AC is all that far off.