Just a quick feedback based on a single run though :
1:- Crosshairs -some way of telling what you're aiming at would be good, perhaps they could even move out a further distance the faster you move?
2:- Graphics are nice on the helicopter, but the style is incoherent, there's the grass and the water with the fancy shader effects, but then the buildings in the cartoon style - maybe keep everything in the cartoon style. Including backdrops.
3:- Can't wait to hear some sounds. :)
It reminds me of Red Zone more than Desert strick being as you've got it top down as opposed to shallow isometric like desert strike had.
Maybe you could throw in some Red Zone style parallax on the taller structures to make things more 3d. :)