Wow, the Bad Company 2 beta is actually fantastic. I just played a whole bunch of rounds and it's just insanely fun. The only downside is the fact that only 2* Playstation 3 owners own a head set. So many times I've wanted to yell to my team "ARGH he's behind you!" or whatever but I can't.
The sniper rifles are really fun to use and setting up overlooking an objective and picking off the dudes as they try and disarm the bomb is great. My favourite sniper moment was killing a dude and then killing the medic that rushed over to revive him RIGHT before he managed to revive him.
The assault class is ok - I'm not sure being able to give ammo out is that useful but it's cool having an endless supply of M203 grenades :D I just unlocked the second rifle and it seems much better than the first (which is mostly due to preferring the ironsight)
The medic is my favourite class. Being able to bring people back from the dead is just awesome. Also setting up little triage centres where I just spam out a bunch of medkits and people can fall back to it or pick up some health as they pass. The medic has a massive machine gun which just makes him awesome. I have the faster sprint perk on my medic so I can dash out of cover and revive someone.
The engineer is my least favourite class. It's great that he has a rocket launcher but I don't really find the tanks all that bothersome for the most part (and the snipers det packs deal with them quite well). His SMG is ok in tight quaters but it basically forces you to stay in the few buildings or alleyways and that's just not my style.
I've not spent a lot of time in the vehicles but I enjoyed sitting in the gunner seat of an M1 just picking targets (if you hit the back/select button when looking at a bad guy or enemy vehicle it reports their position to your team - much better than the auto report on hit that BC1 had)
Definite purchase for me - PC or 360 though? I'm not sure - I can imagine snipers owning the game on PC unless they do something to balance them - a good sniper on the PS3 can dominate so I hate to think what a good mouse sniper could achieve!