I hadn't played it for a while (pretty much the day modern warfare came out), and I got the dlc last week or the week before. The island of dr ned was irritatingly easy... needless to say that complaint is out the window in the 'dome. It took me a while to get past the 1st round in one of the rooms, only to discover I have to do that shit 20 more times, 25 CONSECUTIVE waves of enemies per round. 3 rounds to the first mission, shit.
Max ammo, and health vial's are your best fucking friends.