I started to play Multiplayer this weekend after polishing off all the single-player achievements.
If they could patch away the severe Netcode issues (in my wildest dreams I couldn't have imagined they would release a game nowadays that suffers from netcode issues that would make Doom 1 cry), they'd have a pretty fun game.
"Then there's the double-barreled shotgun from Doom 2 - no-one within your entire household could be of any doubt that it's been fired because it sounds like God slamming a door on his fingers." - Yahtzee Croshaw