Honestly I enjoyed it. It is quite short in comparison with the other games, but it is very fun. It is interesting with almost everyone having automatic weapons as well. It is very hard, a couple of lucky shots from the enemy could turn it all against you.
I think a lot of peoples problem is that they were expecting large battles and tanks and air strikes etc, whereas you actually just control small squads in mainly stealth based missions.
As a veteran of RTS' I think you would probably enjoy this game, just be warned that when I say this game is pretty hard and challenging, I mean it
. Often enemies will get around you and you have to really think about what you are doing.