I'll get the cons out of the way first, then move on to the pros.
For some reason, the girl in the swimsuit just doesn't work out for me. It would probably make more sense if she was wearing some kind of robotic suit, or at least holding a magic staff of some kind. That's just me though.
My biggest bother about the gameplay is how you're suddenly taken back to the title screen upon death. It would feel more polished if you had Nut Girl explode/vanish and display some sort of GAME OVER text for a few seconds before returning to the title screen.
That being said, this is a fun little shooter, and I have to agree with Toxic on the charging system. Unlike most other side-scrolling shooters i've played, there's actually a reason to let your finger off the fire button every now and then. Combined with the leveling system, it adds a whole new level of depth and prevents this game from being just another generic shooter.
Cool game, but a girl in a swimsuit, eating nuts for health? I'm not gonna say what it reminds me of but it makes me feel a little uncomfortable. But great game with fun gameplay and cool bosses, shame my Laptop lags bit though.