Ok soo i'm a very dedicated fan to uncharted 2's multiplayer portion. The cooperative modes especially but what can really drag down the fun and give a huge rise to the frustration....is those muthafukin chokers! Some could see them as just an obstacle to rack up the difficulty and to make sure your alert and of course to really force your team to cooperate, but so often have they seemed to just...appear...without much notice I'll feel i'm being cheated.  
They don't speak or make any noticable sounds so there very hard to foresee if you happen to be looking down your sniper scope, more so you can't even melee the bastards! I mean even if you manage to get to them first. When they grab you too, the fact that the characters can absolutly dropkick and ball jab soldiers to death, I don't see why there couldn't be some sort of counter move available instead of just tapping triangle to only buy yourself some time from the neck snapping. 
 
Plus tapping triangle constantly, when saved, can usually have me accidently switch through like every weapon in close promixity...which is also mighty annoying =/  
 
But still I could see why some can just live with them or even encourage these types of enemies because admittedly it makes the game incredibly tense when you have a swarm of them charging at you or if you happen to be the last player on your team alive, but the fact that theres really not much way in terms of countering them if their close enough...my opinion over them is that their just a little unfair. Sooo, am I the only one? or should i just quite my whining and put up with them?

They are pretty annoying, but hopefully I'll get better at avoiding them as I play more.

"Well the whole point of co-op games is that the enemies appear off screen and in Uncharted they come down from ledges and the like "

I think theyre a good idea - mixes things up a little. The only bad situation that came from it was when I was playing with someone who clearly didn't know the controls, and so would come right up to me to free/revive me, but not actually do anything....soooo frustrating.