What I find interesting is the similarities between the MW2 release and Halo: ODST.
Now, I'm no Halo defender. I can't stand the franchise and think it's incredibly overrated. But when ODST was released, the main gripe was "they're charging full price for this game...when it's just a 5-7hr campaign and re-hashed Halo 3 multiplayer?"
Then you have MW2 released, and it's being hailed as GOTY by many reviews. No one seems to notice that the campaign length is about as short as ODST's...and the multiplayer is pretty much the exact same as MW1. To be fair, the maps in MW2 are new (ignoring the map or two that are constantly redone for each COD release since COD2 or possibly earlier) and there are some new gameplay additions...but is that enough to warrant the difference in reception?