Not a tank player in this game but its obvious that the camo bushes gives you some kind of advantage in realistic battles. Probably good players will do good even without it and wont have problems playing against someone that has it.
500 ge its not alot but if u have to spend 500 ge just for 1 tank , its gona cost u much more if u want to put it on more then one. Anyway it a free to play game, and compared to most of other free to play games , you can play this one and not pay a dime without any significant disadvantage. Plus they are doing alot of events where u can get alot of premium stuff.