The sniper mission is annoying for a couple of reasons. Firstly, there are occasions when the remaining sniper for a wave gets stuck inside a building. That's pretty rare. That is also the first mission where hot swapping between you 4 different personnel is really important. Sometimes I still ended up having to get down off of the buildings and search around for the last couple of enemies. The gps (why gps?) is useful for that.
All in all I enjoy the game, the multi more than the single player, however I really prefer to have at least one person I know playing as well. Takes the game to a different level.
Besides, I'm not that good at it.
Thinking about picking up the pc version, but I have a horrible vidcard and no money to upgrade it.