Quitting resulted in a restart. 1/5 lost all my progress, should be a warning I was nearly finishing the game. I managed to screw up one map and didn't want to suffer through all the waves so I pushed quit.
I think snipers should be more accurate when aiming, I mean some guys can use m4 or some other rifle like that to shoot at me and kill me even though I am behind cover and my head only shows up, but my sniper can't hit them.
I like the battle mechanics the most, It's the same as in Heroes ;). You might want to shorten the tutorials and make it a bit more simple explained, I didn't read anything during the tutorial, besides the game is really easy to learn.. Why bother adding so much text in to the tutorial.. I can't help you with anything else as I don't know to improve the game, it works like it is.