@Brodehouse: Yeah, I agree on the Multiplayer - overall, I think they've done a great job designing the multiplayer maps. They aren't so interesting when you encounter them in the main game, but most of them are very interesting when played in the intended setting (multiplayer). Most of them have a lot of interesting side-corridors for flanking and escape... there's a lot of cover, but also a lot of places where you (and the enemy) can invalidate said cover by use of higher ground.
It's been a long time since I played the Mass Effect 3 singleplayer, but... besides the whole Gears of War issue of "Hey, there's a bunch of waist-high cover in this room - I bet I'll do some shooting here!", I can't remember any issues of getting lost or finding it directly uninspired.
It's interesting how many are so dismissive of the combat in Mass Effect, meanwhile, I've easily put 100 hours into the multiplayer, just because of how satisfying it is. Sure, there are some stickiness issues witht eh whole "run on the same button as take cover", but that's generally something that you learn how to deal with :)