I'm coming from CoD and I still having a small bit of learning to do, but I've gotten the hang of it for the most part. I'm sitting at a K/D of 1.5 right now, but I'm getting progressively better since I've learned to manage my suits abilities and power levels. I'm happy with the transition.
I popped in BO last night for the first time in two weeks to play with other friends, and it was horrendous. I could immediately tell the difference in the latency issues and bad gameplay. Don't get me wrong, I love CoD, but Crysis 2 has become my new love affair with online gaming.
I see a lot of these rants as well and don't get it. Like you, to me these people expect to be playing a different version of CoD. Same kind of gameplay, mechanics, etc. and play C2 online and get absolutely murdered. This game takes skill to do well, even decent, not just point-n-shoot to get your "1337" game play.
I find this is why a lot of people who piss and moan about playing like doodoo and threaten to leave the game or have already left to go play another game that a child can play and do well. Just my two cents.