I actually haven't played BF2 since I started playing this game. IMHO I thought Joint Ops from Novalogic was a better game. It had high grass you could hide in and snipe people from long range. It was so fun being sneaky in that game.
One of my favorite things to do, was to choose a uniform that looked pretty close to the enemies uniforms. I'd then sneak over their their heli spawn and wait by a chopper. With JO you could jump in the back of a heli and just stand in it waiting 4 bad guys to show up.
Typically they were so hyped up they were going to get to fly the chopper or get one of the guns they would never even notice you were a bad guy. If the first guy didn't notice you then it was pretty sure bet no one else would either. Once the chopper started to fill up no one would pay attention to you so it was safe.
I'd then wait till the chopper was in the air and then start knifing all the bad guy and steal their chopper. Oh man that was so much fun to do. I almost want to reinstall that game thinking about it.
This was JO btw
http://www.novalogic.com/games.asp?GameKey=JOCA#ss