It was very fun. I liked the perspective aiming, it was not hard to get used to. Maybe the power up usage could be improved if you won by chance defeating an enemy and not have it "for free" in certain levels, since it does provide a big advantage. Last screen (I assume) had an absurd difficulty increase, even with 6 bullets, after I got hit 2 times and lost the powerups it was impossible to stand anywhere withouth beign hit.