Very similar to the original, but not as good.
If you've played Crackdown, you'll be instantly familiar with Crackdown 2. That's because you'll be seeing the same map with the exact same graphics cut and pasted right out of the original. The story has changed somewhat, you fight a gang call Cell, and now there are zombies. While its fun fighting them, the repetitive missions involved in ridding the city of them leave a lot to be desired. You'll do the same 2 types of missions over and over again for hours, then the game will be over. There is an online competitive multiplayer, but even if you manage to have some fun with it, it doesn't come close to making up for the weak campaign.
The fun in Crackdown 2 all comes from screwing around and searching for orbs. Exploration is still enjoyable, but the climbing feels a little less precise. I really enjoyed running over hoards of zombies in the agency cars, but as fun as that is, it can only entertain someone for so long. Other distractions include new orbs that run from you, requiring you to chase them on foot or in a car. There are some races too, but really thats it. It is fun, just like it was fun in the original, but its too shallow to support the entire game.
In the end, you have a worthwhile title that shows potential of possibly becoming something great. If this were not a sequel and this was the first time of seeing these ideas, I'd be impressed. As it is, you'd be better off replaying the original Crackdown again if you enjoyed it. Hopefully they'll decided to put effort into Crackdown 3 and make the series into the crazy fun and innovative franchise that it deserves to be.