I did have fun playing through the levels, but there were a few things I felt detracted from my fun.
1. Probably the biggest thing was the cannon position. Each level it started out in a worthless place, and every time you reset the level it moves back to the worthless place. This got annoying pretty quickly. It would be best if the cannon stayed where it was last at.
2. And just because it is fresh in my mind, although some people may prefer it I would rather not be put directly into the bonus level. Not a fan of the juggling games, So I would skip it.
3. Although it isn't clear how the score is created, judging by the high scores table it looks like you may want to re-figure that (as all of the high scores are 32000. My guess would be it is simply based on if you pass a level and if you make par or not, not the total number of shots fired or anything like that (one would expect more variation).
4. I noticed that very rarely did the no-cannon zones play into the puzzles significantly, even though it was a significant part of the game. If you make a sequel consider making more puzzles based off of your limited points of cannon placement. Perhaps this would make some of the levels that had a high par but were easily done in one shot make more sense.
Overall though it was fun. But could use some work. I think that 3/5 8/10 is fair. Keep up the good work.