I've been playing it since day one launch and I believe they have released one update, which I feel really improved the game. You can only play as German or US tanks, TD's, and SPG's. you can only use up to tier 6.
So far if you've played it on PC which I feel half the people who are playing it have then you have a slight advantage of the layout of the three maps.
I play SPG's only and have played it so long now to the point were I can hunt for enemy SPG's and get blind fire kills.