My son and I enjoyed the first one, so we gave the sequel a try. It's a run of the mill cover shooter, the couch co-op aspect is what really makes this one fun, however some issues we encountered included:

Lots of stuff was removed that was in the previous game. Very little back to back shooting, almost no teamwork required missions, no car door shields, no unique bosses.

The 'morality' choices didn't add anything to the game, quite the contrary, we would have preferred they be removed. Although they may have inspired Spec Ops: The Line, released two years later. We got tired of trying to save civilians half way through and just gave up on it completely.

Our biggest gripe was the weapon upgrade system though. Throughout the game you find cash, and you can use it to buy weapon upgrades. It's a tedious process as you have to be in a certain location, you have to request to do it, your partner must confirm, you choose the upgrades you want, it makes you confirm after each purchase, and then if you die in that mission, it resets everything you did and gives you the money back without even telling you it happened! It ended up being a serious waste of time as we bought the same things over and over only to find that they didn't 'stick' because we died somewhere along the way. Frustrating!

In the end we still had a good time racking up the body count, but we liked the first game a whole lot more.