I stopped playing a long time ago. It's fun but kind of gets boring after a while. Although it is nice when they add new maps and stuff. Hopefully the totally new version based on the Unreal Engine 3 will be out before too long.
I got sick of how the devs promised features and then kept pushing them off saying "oh it'll definitely be in the next version." I mean, it's a free game so I shouldn't comlain, but there are certain issues which the devs always put off. I've also noticed that each new version had horrible lag issues for the first few days/weeks. Actually, in general the game used to have lag problems which were hit or miss. Dunno if they fixed it.
Some traditional gaming conventions don't apply to AA so it can be a much different change of pace. For instance, don't plan on bunny hoping or even sprinting very far, gunning while running, etc. And weapons accuracy is affected by so many factors you'll think you're playing a game of DnD with 20 sided dice. It's not just your stance and what weapon you are using, but also your fatigue, your health level, whether or not you're bleeding, whether you are using the weapon you spawned with, whether or not you have your squad leader next to you(snipers get boosts if they have the leader/spotter next to them), and several other factors.
Another thing is frags, rpgs, etc. Most games have a pathetic blast radius for explosives. In AA, there is shrapnel. So you can stand next to a nade and maybe live, but be standing literally 30 feet away, and get ***-****ed by a stray piece of shrapnel. It's completely random, sort of like in real life. So if you see a nade, go prone or get behind a wall. Running won't save you.
Another big thing is that everyone spawns once during a round. While this is no different than games like CS, AA has a much slower pace, which combined with the fact that most people like to camp if their team is dead, makes for excruciatingly long waits between rounds if you are dead. Objective time limits are like 5 or 10 minutes as opposed to 2 or 3 in most CS servers.
Oh, and cheating is pretty rampant in AA(or at least it was). Punkbuster doesn't work nearly as well in AA as it should. so many aimbots its rediculous. It's not like in other games where people are just so good that they get instant beads on your head, and you "think" they are cheating. The nature of AAs aiming and accuracy system makes it hard to run and gun and get headshots left and right. You can't take on 6 guys surrounding you like you can in BF2 or CS. So when someone drops everyone they run across left and right, you know something is up.