i only have a couple of complaints:
lag: seriously, it has a huge effect on my game. I live in alaksa where i have a perpetual three bars connection at best, my k:d ratio on average is 2:1. But, when im the host it jumps to 4:1 and sometimes higher, its a smoking gun on how much lag affects everything. Sadly when im hosting, that means everyone else is lagging and thus, a closed or merged lobby.
Spawning: in no other game have i had a problem with where i spawn. I have had numerous experiences where i will spawn and get killed two seconds later by someone who just happens to walk into the room, and like many others, killed by air support while being spawned with the rest of the team outside, MW2 is in desperate need of an at least 2 second "spawn-shield"
Other than that, i have no real complaints. Sure its annoying when in objective based games it seems like im the only one trying to do anything. "am i seriously the only one going for [insert objective here]?" is a common saying of mine during these matches. As for the nuke complaints, i have only seen the nuke three times, once used against my team and the others against the enemy. Like others, ive noticed that many of the complaints seem to be either of lack of teamwork (not going to change), poor skill on the teammates' parts, or players whose sole desire is to get as many kills as possible using the cheapest tactics. (dont get me wrong, im all about lots o' kills but you will never see me with a noob tube/OMA combo or any such cheap setup)
I also noticed earlier someone mention how they are consistently paired with crappy players. I too experience this phenomenon, there are many matches where i will have 2.5k+ points in tdm (frequently the match leader) only to be matched up with every player with under 1K, while the other team has every player in between.
One more thing, does this happen to anyone else? You decide to go stealhly and take the long route 'behing enemy lines' only to realize that the enemy has beated your team back to their spawning area and now your team is spawning near you, only for you to try it again and have the same thing happen? frustrating stuff....