It's not terrible, but it is extremely boring. The A.I. is not bad, I like how everyone will run for cover. But the friendly A.I. sometimes seem to think the object of the game is to grab as many bullets as possible!
The game is lacking in some areas when compared to Ghost Recon 1. The weapons are unimpressive and very limited. There's only one sniper rifle, and it's pretty crappy. Only one heavy machine gun, two rifle, one submachine gun (maybe two). The good part is that they're all fairly customizable, but that doesn't really change their performance all that much. It just doesn't make sense. For example, the sniper rifle looks like an automatic but acts like a 1-shot bolt action.. I'd rather have a PSG1, HK M50, or a L96.. Even a Steyr Scout or Robar would do.
The game does introduce some cool elements to the gameplay, but it all falls short of making a good game. It's supposed to be a tactical shooter, but it feels too much like an action shooter. One part that's a little frustrating is having to shoot somebody more than once (occasionally more than 3 times) to take him down.
I think the real joy of the game is in the multiplayer. Unfortunately Ubisoft/GRIN dropped the promised multiplayer coop campaign. Instead you have the single-payer campaign for coop. They're considering making a mission pack to include the originally intended coop campaign, but there's no official word yet.
The multiplayer side suffers quite a bit as well. One thing which everyone finds absolutely frustrating in coop (and it hasn't been fixed yet) is that no matter what happens, if the team leader dies, the mission fails. Furthermore, you can't choose who the team leader is, it will always be the server host.
I haven't tried DM or Team DM, but I hear it's not bad. I love coop.