Okay, here we go... time to harsh your mellow, dude.
Upon starting the app I get this error:
I have no idea what it means, but it lets me start the game anyway. Strange.
Anyway, feedback time...
Robochick's missiles are slower than she is, which looks kinda odd. If you're flying forward at full speed, then the missiles look like they're spawning behind her. I know it's important to have speed and maneuverability when you're a sexy space robochick, but you could probably get away with slowing her down a little because she is pretty zippy.
And I hate to say it but the new gun arm also looks off to me. It looks fine pointing forward, but not when it flips around to shoot behind her. I would recommend one of two things:
1. Make it so she can't shoot behind her. Restrict her aiming to an arc in the direction she's facing. You could compensate for this by having a "Lock" control, so when the player is holding down Lock she stays facing the same direction but can still fly around (that way she can fly backwards to escape from an enemy while still plugging it full of missile).
2. Make her gun arm the front-facing arm, and have the arm sprite change when it's max swivel point has been reached, like so:
That way you have a front-side arm and a back-side arm so that it doesn't look like her arm is just going around in bone-twisting circles. Also the far arm isn't passing in front of the body this way. You'd still have a kind of swivelly looking arm though.
Personally I think option 1 is the better option. Not only would it stop the swivel effect altogether, but ultimately it would make for much more challenging and dynamic gameplay. Not to mention you wouldn't have to to do any further spritework on her arm.