Yeah i got that same feeling although i never played COD4, COWAW was my first COD game and FPS game, but MW2 dosent addict me as much as COWAW, MW2 is the better game though, by far...
But On Topic: I don't see why people are so easily bored. Kinda sad that people have such a short attention span. Oh well. MW 1 is still fun, but MW2 is a much needed refresh and I don't see myself being bored for a long, long time [possibly never]. The only time I'll be putting it down is when God Of War 3 comes out. That will be amazing.