I'm loving the Famas <3
Currently my favourite assault rifle, but I'll have unlocked all attachments soon, so I must move on D:
I'm also a fan of scavenger - really useful if you aspire to aquire long kill streaks, which I often do (not to toot my own horn), so it becomes really useful. I especially enjoy throwing random semtex bomb so I can pick another up

Also very useful with the AA shotgun.
I'm also a fan of using the throwing knives. So. Much. Fun. And so very satisfying when you get a kill with them. Though I'm finding it annoyingly hard to aim with them in hardcore mode D:
There are a few things I've come to hate it though. Most people in MW2 are using varied weapons - which I enjoy seeing, as it promotes balance (though I've got serious doubts about this game having balance) but a lot of players are also using some weapons which seem to 1-shot kill (FAL *cough*), though this is likely with stopping power.
I'm also finding the match-making system to be somewhat lacking, as I often find myself with a team of lower levelled people against level 50+ players, which just screams lack of perfection. This may be console I'm talking about, but the first MW's MM system was also pathetic. I was expecting a goddamned improvement.
But overall, I'd say it's alright. I wouldn't buy it myself (which I didn't), but I also wouldn't disencourage others to not buy it.