[quote name='mywhitenoise']Generally for most games, multiplayer kinda sucks.[/QUOTE]
And say what you want to about CoD, Halo, Gears, etc. They generally do it right. They don't appeal to everyone (and apparently no one on message boards), but there's a reason they are so popular. I'm not a huge PC fan, I do play some, but you can tell the MP is better on PC.
As far as co-op though, you can't beat XBL/PSN or couch versus a PC, in my opinion at least.