To be honest, I like Bad Company 2 a lot more than MW2. (I sold MW2 because of all the glitches and cheating, ruined online play for me)
Bad Company 2 definitely has a larger learning curve, and you have to get a feel for what classes are good for what situation, but once you get the hang of it, it's way more fun and tactical than MW2 ever was for me.
In MW2, you don't need teamwork to win, one person who is really kickass can, for the most part, dominate entire matches with little help from the team.
In Bad Company 2, one person doing super good doesn't make a difference at all unless the others are trying to take points or use the equipment the classes have (ammo crates, defibrillators to revive, target marking, repair tool, anti armor, etc)