Hey buddy, I tried that level atleast 3 times before I passed it, here's a few tips which I think should help you
1: walk, don't run, look around, don't just rush
2: most of the snipers are infront of you, or at the top of the roof, and YES in buildings, you won't miss them once you're facing that direction
3:Heard of QUICKSAVE? if you're still trying to get accustomed with the style of playing, SAVE after you killed an enemy sniper, this will buy you time of locating the sniper, get KILLED? no problem, QUICKLOAD and find that killer. Quicksave is F5 and QUickload is F9
4

on't blame the game for being too hard etc etc, blame yourself first for not THINKING!!
5:Kick yourself in the NUTS if you still can't pass it, it might give you some MORALE boost
