Well, I agree with both Johhny and Dex on a lot of their points, but I think at the same time I'm more than a little biased because I've sunk more time into the Battlefield games than any other FPS, and maybe any other game series.
I only have a couple points here because most of my opinions on all of this are pretty boring.
First, in regards to the Recon class being broken, I wholeheartedly disagree. To me, the Recon class is the most versatile class in the BF games (or at least BC2, the only time I've played the recon class for an extended period of time), and that's why so many people have a problem with it. Because you can play it sitting 3 bases behind and sniping, people do, and because you can run around quick-scoping and one shotting people do. The problem isn't wholly with the class, it's with how people play the class, and unfortunately, the class lends itself to the extreme agressive playstyle or the passive, irritating sit back 3 bases behind and snipe playstyle. The problem with these 2 styles is that one breeds hackusations and the other makes teammates rage at you when they have to respawn and run up to the next base. You can't do those types of things with any of the other classes in Battlefield, and that's why I enjoy playing recon so much in BC2. Unfortunately, I'm not very good at it, so I don't do it very much. Eventually my luck runs out with quickscoping, though, so I kinda rage and go assault or something.
Secondly, I don't really think that BF needs to or has good balance or good teamplay or good anything. I've had some of the worst multiplayer experiences in BF, and some of the best. The reason I keep coming back to the Battlefield games isn't the immersion, it isn't the guns or the gameplay, it's that I've spent so much more time in the BF games than any other series I can kinda pick up where I left off. I keep playing the games because the learning curve is practically nil with the exception of the new maps now. I keep playing the games because they're fun, not because they're better than COD or have great weapon balance or teamplay, because, well, that's in the eye of the beholder. They're not really well balanced games a lot of the time, and the engine is a little broken with hitreg on high and low pings, but the Battlefield series is by far my favorite MP series out there.