It has multiplayer modes but I can't imagine too many people playing them for too long. They're ok but nothing much above the average of what's out there.
Xbox is not as popular with single player because Microsoft haven't focused on that much which to me is a mistake even though they have succeeded massively in taking console multiplayer gaming & co-op mainstream with the 360. If they had made a good number of new franchises like Uncharted last gen they would be strong on both fronts. I thought the 1st Gears had a good campaign though, playing it 1st time is the moment I thought a new gen has finally arrived!