Going with the rehash route...
When I see screenshots and such of MW3, its pretty damn hard to see the difference from MW2. Then again, the same can be said of Uncharted 3 and 2... which by all accounts is an amazing game.
I however can't see COD games as quality games that are worth $60 when it comes out every year without looking somewhat different. It makes it seem very basic. Not saying basic stuff are not good but for $60 a pop brand spanking new...
On a sidenote, Uncharted 3 is a few years removed from U2 and U2 set the quality to be high, very high. So its worth the $60 imo.