Is good, but it gets a little repetitive
It would have been better if you should jump in another places, like a a snowing mountain, and you can play when you go to the ground, not go to ground, then magically jump to another helicopter... maybe you can do this kind of game with a storyline, jumping from the helicopter, then going to a facility (Of course, the facility is part of the storyline) , get some information of the objective, then going to the extraction point, killing enemies with other helicopters behind you.
This is just a idea for a game of this like... and this remembers me a lot from Metal Slug. Anyway great game! :D