Every post here so far basically identifies the firepower of the UAV, however the defined usage of UAV is simply a surveillance droid. While it can call down hellfire it should not be its primary roll. Usually when I man the UAV i use the motion sensor perk and go to max altitudes and zoom around where the enemy are suppose to be giving my team info on the enemy defense as a whole. If i do not have to call hellfire no one bothers to look for me. If you think about it whenever you are looking for a UAV it is because you saw a hellfire come down. If it doesn't come down you don't think its up. The best part about the perk is that it doesn't beep like motion balls do when you are in their radius, thus the enemy can be hiding behind walls, buildings or all the way in the back of the base thinking they are safe and undetected but now you're team that looks at the map knows exactly where they all are and can make better decisions on where to make an assault or concentrate defense.
the motion sensor circle you see on your mini map.. i'm pretty sure it doesn't show up on anyone else's.
Well but the uav can be very usefull in rush mode. You can take out an m-com station easily, if it is set in an building, from far away. Just destroy the structure, the collapsing building will do the rest for you .