Each of your five buttons are mapped to a different action that takes down a different enemy (such aspushing up to take out a helicopter or down to smash a tank) or to occasionally perform a badass slam dunk.
And if you were to be such a badassas to be able to pull this thing up hills, coming down the other side would be a whole experience in itself, considering how much weight you'd now have pushing you down (assuming you did pack some gear in there).