My main combo is the five-seven/sc3000, but lately I've been using the fully upgraded MP7A1 with my five-seven. I like the mix of power and rate of fire. Also, it's compact enough to use one handed when you're hanging from ledges and whatnot. Very useful.
I knifed three guys in a row the other day, and the last one had silver dog tags. Three medics had my squad pinned down, 2 were firing and one was healing. I flank them while my squad draws their attention. Knife the healer as he turns to face me, then put it in the back of both of the other guys necks as they continue to shoot, unaware of my presence.
I've knifed a lot of dudes online in my days, but this particular instance was special.
I don't like the fact that no matter where I was on a map, I had to worry about being shot from all directions. The way the spawn system works, finding enemies isn't about out smarting them, but rather running around and hoping you see them before they see you. No one plays as a team no matter what game type you play. The whole thing is a mess. It feels like an arcadey shooter for the ADD generation. I played the hell out of the original CoD4 online and loved it, and on paper the sequel should be better. For whatever reason, it just doesn't click with me any more.
Oh yeah, and Battlefield 2 came out so I had no reason to play MW2.
There are lots of explosions and cool things going on, as long as you aren't shooting with standard weapons. That is when the game is at its weakest. I'm having a blast doing crazy shit though, I imagine I will play it for a solid week or so then send it back to Gamefly. Perfect rental.