Not at all what people wanted it to be and could've been so much more.
The demos at E3, etc., were so preset, the developers had everything at their disposal. Personally, I never got anything cool past the RPG Rocket Launcher. Even with this, the gunplay is probably the weakest you could come to in a game. You get put down so fast by the overwhelming AI that just knows how to shoot better than you, plain and simple.
Vehicles. Hijacking them used the same animation every time, even the same button combos. Driving is very, very bad. If you come a centimeter too close to a small rock, or in that case, a pebble, or a sidewalk, etc., you lose 10% of your vehicle's health. It's a terrible way to get around, but better than getting destroyed quickly by almost everything else in the game. In terms of voice acting and humor, that was about the only good part, besides the explosions. The story was, or course, pretty dull. The graphics were so buggy and smeared at most times, it was frustrating to get stuck onto something. Co-op isn't different and might as well not have been added to the game at all. All in all, I wouldn't recommend Mercs 2. If LucasArts returned to their developing posts for the series, Pandemic would have been out of development, easily.
Gameplay: 4.5/10
Graphics, Game, and Character Designs: 6.5/10
Story: 3/10
Voice Acting: 8.5/10
Replay Value: 4/10