Addicting (when you give it some time). Big minus because of huge amount of freely rampaging hackers.
Lots of settings for every player and computer to create the best visual feeling.
I had Ati Radeon 9600XT and it didn't work well on that card, you should at least have PCI-E bus card, otherwise don't bother playing.
Audio: 4/10 Not much to say about music and other sfx, they just are. Few songs,wich are just some sort of drum based. Exposion and weaponfire sounds aren't that amazing, you can't hear them from small distance at all (in real life you can hear weaponfire miles away ).
Game Core/Engine: 3/10 About only good thing about game engine is ragdoll effect. Engine contains lots of bugs, for example: MP5 submachinegun/M24 sniperifle occasionally wont inflict any damage(its not my internet connection,rly).;Press reload button and turn around fast, your weapon is reloaded(that's weird?).;You fall underground at time to time.;Sudden D/C from master server(that may be engine bug).;Sometimes you spawn in air at CQC maps with knife on your hand.. and the list goes on and on and on and on....
Gameplay: -10/10 That's right, big minus. Why? Because of freely roaming hackers that ruin the gameplay totally. Where are all the K2 admins when you need them? Hello?
At least you can play this game for free, i wouldn't touch this with a ten foot long stick if it would cost money per month,like WOW.
Then there is PREMIUM,that is totally rip-off. Why would someone pay 5-15$ for premium + more money for weapons and other junk, like extra slots. when you add them all together you have been spending nearly 30$, with that you can buy A real game with (supervised) online play.