I agree with the comments about the ninja's behavior. I would also like to see the mouseover to collect coins go away - it's distracting enough with a mouse and frankly irritating on a trackpad. On later levels where you need to pay close attention to ninja health it can be too distracting.
The targeting/prioritization is a problem - if there's only going to be one priority it should always be closest to the endpoint. I can't tell what the priority is now.
Well, on the one hand, this game delicately and thoroughly cleanses the herpes sores on a dead donkey's balls. On the other hand, I won the first time through. You'd think that would be worth something, but no.
Uh. Okay, I get a screen that says, "BAM RESTART? You died. YOUR SCORE:" Then I click restart and all I get to do is drag a black square around a white field with a '0' at the bottom right. I...I'm not a crap burger, am I? I don't want to be a crap burger. No sir.
3/5. Work on the graphics a bit - just some polish - and get rid of the creepy voiceover - text fading in and out at the bottom of the screen or something would really be better.
5/5! Wait, no, 1/5. Seriously, give some basic instructions and it'll be an easy 2. How do you use nukes? I got killed before I figured it out and can't be arsed to play again.
I want to give this a 5 but it's too buggy (see Amigaway's comment, I ran into the problem with the platforms). I'll up my rating if/when that gets fixed.
Physics: Mostly the ball doesn't feel like a metal ball bouncing off of various things - it feels like it (or the surface) absorbs too much of the energy. That also makes it feel like you can't build up the kind of velocity you can get in a pinball machine.
Glad you like it!