Alright, sorry.
Why do I think the game is ruined? Well....
For starters, the spawn system is horrible. I've been put in front of enemies countless times, not to mention the number of times they've spawned behind me. I know some of them were just tactical insertions, but for the most part, it was the game being incompetent. I was playing a match once where the score was 7300-7400. I killed a guy who the proceeded to spawn directly behind me, and knife me. Yes, there was no tactical insertion.
The maps also really bother me. A lot of times, when someone is taking cover behind a wall, I can only see the very tip of their head. And yet they can still see me perfectly. This was present in COD4 and WaW as well, but it appears a lot more in MW2.
Killstreaks are also a pain. I know they're balanced, and it isn't hard to shoot them down when you have a good team, but that's just it: I rarely have a team who shoots down air support. When I hear that NPC voice yelling that an enemy chopper gunner is inbound, a feeling of dread grows within me, knowing that I will be the only person to shoot it down. And while I'm trying to shoot it down, it's sitting there spraying in every possible direction, killing me in the process.
Then there are all the glitches this game has. I can understand issues with the maps' geometry, that's bound to happen, but things like the infinite care package glitch, the bling'd 1887s, the javelin glitch, all of those are extremely game breaking to me. I joined 3 games yesterday, and in all of them, someone was doing the infinite care package glitch. The amount of air support was ridiculous. I would shoot down a Cobra just to have it replaced by a Pave Low and a Harrier.
My last issue, aside from the lag, is balance in general. Games tend to be very one-sided, with some games ending 2700-10000, or 41-200. On top of that, you have things like the models and the tactical knife. The models have way more range than they should, making it extremely hard to kill people using them. My issue with the tactical knife is that you pretty much always lose knife fights, even when it seems that you knife first on your screen. I wouldn't mind this if people didn't run around using it exclusively.
So, yeah, that's why I think that.