[Sledgehammer427]

The game runs pretty well in my opinion.
Balancing can be a little funky, I haven't played in ages, but when I played, I had a stugIII with the highest level gun, and I kept getting matched with guys who could kill me in 1 shot, and every once in a while the matchmaker felt sorry for me and would put me in a really balanced room, where I could get a couple kills and be happy.
It seems well built the last time I played it, in terms of the kind of fighting. I had a Tank Destroyer 90% of the time so I ended up having a crew trained in stealth, with the camo netting added and some other stuff, so people usually wouldn't see me until I started shooting, and that gets to be kind of interesting.

As for spending RL money for in game stuff, it goes as far as you want it. I've done it myself and it gave me a pleasant boost when I was getting tired of the same crap.