My friends and I are absolutely loving BC2. We only play together, but there are always at least a few of us on since most of us work 9-5. We're all totally hooked.
The sprinting (on rails) can be a little annoying at first. It's something I got used to quickly and is now just a game mechanic for me. I'm assuming they did this since you have unlimited sprint, but who knows.
I'm realizing how fun each class can be, and as someone above pointed out, how useful they can be even for an adept player. Last night as Medic I literally did nothing but sprint from dead body to dead body. I lead the team by a LOT. Kill/Death ratio != win in this game at all.
Here's my new routine on rush:
At the beginning of the map I use engineer. Both on offense or defense.
If offense, then I get in the biggest tank I can find (as gunner) and go into battle, repairing whenever we take damage. Having a good driver is important, and by good, I mean not some retard who goes straight into the middle of the other teams base at full speed. It's important to move in slowly as defenses are gradually depleted.
If I'm on defense, I use my AT mines and sprint as far as I can (without being in danger), and throw mines all over the place. *Note: Mines will stay even after you die or even change class!!! I got like 300 points yesterday for a destroyed vehicle as MEDIC from a tank hitting an AT mine*. After I die, I change to either assault or medic, depending on how close to the bomb sites they are. The closer to the bomb sites, the more healing that can be done quickly and efficiently.
I rarely use recon. I'm not a recon hater, it just seems that only about 1% of snipers actually do their job. If you play sniper a lot, the most important thing you can do is mark, mark, mark. Hit select constantly. You will accidently mark people and its a huge help. In addition to that, make sure to be calling in air strikes and use tracer if possible.
I'll post more later!
Another side note:
Assault and smoke grenades = <3. I swear, a few smoke grenades can change the entire course of a game SO fast. I see the SAME thing happening over and over on rush: The attacking team will take one site, but they will be stuck and have trouble taking the 2nd bomb site. So what happens? Half the team switches to recon and tries to pick off random dudes.... ooook, well, wow, that doesn't help anything at all. A few guys will select assault and try to gun people down... but ZERO progress is made. Here's what you do: Lay down an ammo container, and spam like 5 smoke grenades. Run into the bombsite, plant bomb, and start owning fools.
Try it, it seriously does wonders. At the very least, don't keep doing the same non-working shit over and over...