Well in the case of WaW what MW2 will do for you is actually be a good game, which WaW was not.

WaW offered absolutely nothing and is terrible in my eyes. You just have to ask yourself if you care for some more Modern Warfare basically...because its a sequel so no matter what they add , yes, it will definitely feel like Modern Warfare again. That's just how games are, but I think saying you're already underwhelmed by it is a little too soon, seeing as its not out yet and you like the rest of us have no idea what its going to have in it besides what we've seen in a short E3 demo and trailers. I'd say play the game first then give this impression.