So Mass Effect 3 had multiplayer, then it didn't. Then it might of had it, then BioWare wasn't sure about it. Now, finally, Mass Effect 3 will with out a fucking doubt HAVE multiplayer! It is separate from the Mass Effect story and won't have anything to do with your ME1 and ME2 save files. There will be missions to complete with up to four of your buddies and a character select of different species.
Yes, you do need to have the Online pass to play multiplayer but that as easy as just buying the game new. I mean, who in their right mind is going to wait to pick this up used? No one, that's who!