I could argue that ghost was borderlined OP in other games. I like the "balance" they created in BLOPS2.
That is, unless your game consists of sitting in a dark corner waiting for an unsuspecting victim to walk by. The new ghost forces players to keep moving, which I don't see as a bad thing at all.
It was a little overpowered in other games because it did so much. If all it did was keep you off UAV 100% of the time ten it would hardly be overpowered.
You don't have to move much to fade into the darkness with Ghost. You can even stop momentarily before you appear on enemies HUD. You can no longer sit motionless while ADS looking at a doorway. There were a TON of complaints about this in BLOPS1, and Treyarch listened to the community.
I've noticed a drastic decrease in the amount of UAV's being used since week 1. I suspect with more time, they're use will decline even more.
Prestige once, unlock ghost, and don't worry about UAV's anymore. These have been in every game, and they've always been the easiest killstreak to unlock. I don't know why they seem to be such a problem with folks in this game.
I've not had a single game of TDM where the enemy hadn't called in a UAV. It seems the average is around 4-5 per game. The most I've seen in one game was 11 but I had some horrible teammates.