Noticeable deficiencies in the graphics department, the rest is nit picking
I have been a tank officer in the German Army, and this is about as close to the real thing as you can get on a PC. Really. It allows HUGE battles (several hundred tanks all at once!), but the small missions can be equally challenging.
Gameplay simply rocks - be it as a single player, be it in large multiplayer battles (I've read of up to 14 people in the same battle, and played with about six people in a single game myself). Multiplayer supports about everything you can dream of in a tank simulation, including two players in the same tank as commander and gunner. Be it cooperative (us against the computer), force on force (team deathmatch), everybody on his own, ... you name it.
Yeah, I would have sold my soul for it - but 40 bucks did the job at Shrapnel's game store......