Ok, I know everyone is gonna disagree with me on this, but I think UAV's are overpowered. Why do you ask? Because they are so easy to get. All it takes is 3 kills (and with support it doesn't matter if you die). Seriously, the past 3 matches all I hear is "enemy UAV spotted" 3 seconds later "enemy UAV spotted" its driving me insane. I don't want the enemy knowing where I am the entire match. And that is why I don't mind when people use Assassin. Its perfectly fine to use IMO if you are just running and gunning which is like the only thing I do in Call of Duty. When people camp, I don't care if they use assassin, just the fact that people camp regardless of what perks they use just pisses me off.
/end rant
edit: Not only that but because the way the game and the maps are, its almost impossible to find uav's and shoot them down, half the time I'm lucky if I find them. I didn't mind spy planes/uav's in all the previous cod games because they were easy to find, but in MW3 its next to impossible sometimes.
Yes. And No.
It's a perfectly reasonable thing to think, especially with the number of UAVs flying around in one match of MW3. It seems that the skill involved with earning a killstreak has been completely depleted, especially by the support package.
However, the critical error you make here when suggesting that the killstreak is overpowered is overwhelmingly simple:
Call of Duty's base gameplay has shifted so drastically that the UAV, staying almost exactly the same from game to game, has been inserted in a place where its results are drastically more beneficial.
For instance, how fast people die in this game is a huge factor. In previous CoDs (I need not mention Blops) you had a fighting chance to escape gunfights no matter the situation, simply because your character took bullets like a champ. In MW3, a red dot = insta-kill (hence why everyone uses assassin). Also, like you said, UAVs have been obscured into the stratosphere by buildings and fog, to the point where shooting them down becomes a game of Search and Destroy by itself.
The support package gives you the strange option of only picking one killstreak. In all honesty, this should be removed and replaced with the requirement of choosing three. So at minimum, the enemy team must get eleven/twelve points for their next UAV, in which case they most likely deserve it. Assault, I would say, still maintains balance. To call in your next UAV, you need another three killstreak. But why do that when you could use a predator missile instead? Or maybe call in a chopper? Assault has many more lucrative options, while support is a pile of **** with a bunch of radar band-aids.
Lastly, I must say, if you are having too much trouble with UAVs, start running more CUAVs. Poor man's assassin is much better than it sounds. Remember how hard it was shooting down UAVs? Well, the same applies to those pesky CUAVs.
In total: UAVs not OP, other aspects of the game made it run rampant, start running CUAV.
Any other questions, class?