I thought Modern Warfare 2 was an awesome title, did it innovate though from a single player perspective? No, I don't think so, but it was a load of fun IMO. Hell, the multiplayer has kept me going for ages.
But in saying that, I don't think I'll be buying any future COD/MW titles if they're done by Activision (not that I bought any Treyarch titles). The idealist in me hopes others do the same to show Activision and Kotick