This is a very good game, the aiming gets difficult over time without a too steep learning curve. The helicopter got progressivly more jumpy, and the upgrade system was nice.
Now for the bad things:
You got money way to quick, I was fuly upgraded half-way into the game, making the rest of the money a waste, if not for buying more rail ammo and health.
The music got tenous after a time, would have been better to add a couple more sound tracks in there.
The name of the game, does not suit the gameplay at all. Even if it does run parrallel to Indestructo2tank, dont make the title Indestructocopter as it makes us think "Oh its just like the tank one, where I shall drive my helicopter into things" Which makes all people who think this very annoyed that it isnt.
I for one wanted that idea of the copter flying into things to get points, but if I didnt, this would have been a good second choice.
Overall Its a good game in its own right, but dont name it something just because its in a series, It gives off that little misconception to gamers that this will be exactly like its predcesser, which it obviously isnt.