I have to admit, I thought it would be a lot better than it actually is. There are great things about it, especially how well BF2 keeps track of your statistics and such, but the game as a whole is lacking.
The only way to advance quickly through the ranks is to fly a plane or more specifically, a chopper. Sometimes armor is good too but I can rake up the points (and kills) like nobody's business with a good chopper pilot. We go from place to place and land on the flags, capture them and take off, killing people as we go. It's so easy and takes such little effort. On the other hand, I personally REALLY enjoy being an infantry man because it takes more skill than would a jet fighter or chopper... and as a result I get pwnz0r3d for it. If you are not the USMC, it's extremely difficult to kill choppers because the anti-tank gun can't aim to hit the chopper (ie, guiding the missle).
The game isn't bad. I was stupid and when I got my first unlock, I chose the sniper rifle thinking I could actually make a difference, but unfortunately that's not the case -- I just continue to get owned and maybe I'll get a streak of kills but eventually... it gets boring and I go back to the chopper.
And my biggest pet peeve... I CANNOT MAP THE KEYS PROPERLY. The BF2 default loadout is stupid (for me) and unfortunately the keymaps won't change properly either! The netcode for this game is pretty pathetic as well, as the lag gets unbelievable and the game gets very slow at times. I choose fast servers with good ping to me, and even still it will happen. It never happens in any other game however, so I find this a problem with BF2 and not my connection (which has always been fast).
The game could be great, but unfortunately it's SO tilted to the bias of armor, choppers and jets that playing an infantryman seems to be of little consequence. I play spec ops a lot, and I'll blow up the radar, UAV, and I get 0 points for it. And that would be my function, right? To take out the infrastructure? But a chopper pilot can get 200 points in a game just by hopping one place to another and getting killed maybe what... 2, 3 times if you're good, with good gunners?
There's little point to the game if you are playing as an infantry guy, and that's the most annoying thing about it.