The first subject I'd like to talk about its the most important the guns. However that's much too broad for one post. So lets start with oh I dunno the always fun sniper rifle.
Personally I like the snipers from cod WaW much better. Mainly because you can remove the scope and you have a much smaller window to hit or you will miss and possibly get your shit rocked, thus making the game all that harder.
MW2 snipers almost seem to fire two bullets at once. In many killcams I have see the guns fire two bullets at a target thus killing him. The fact that you can't have the gun without a scope seems like it could be a dissapointment, however with all the attachment you're sure to find something that you like.
Anyway we all know all snipers can't compare to the MP40 :P
Feel free to leave your thought and comments :)