Problem is it takes forever unlock new things and the unlocks are symmetrical, so their isnt a huge incentive to play both sides, you might be getting slightly different weapon and tank unlocks but you are ultimately unlocking the same classes at the same level for both sides.
It would be more interesting if the germans and russians had an assymetrical reaserch tree, for example give the Germans the flamethrower or another assaultier weapon at an earlier level, while giving the germans the Engineer at a later level.
Soviets, played Germans in all the tests and usually won, I want to try the Soviet experience and DP and PPD are just way too good to be fighting against again