Very fun game. It can be hard, but it's never unbearable! (has someone already made that pun?) Definitely worth completing entirely, though I do wish some medals were worth more than others. Maybe have "Achievement Hunter" worth 100pts, while "Shiny Treasure" and "Congratulations?" are worth 25pts.
I'm curious about the name. Is it saying that the bear has a leap jet? Is that a type of jet? Or is it telling the jet bear to leap? i.e. Leap, jet bear!
The music is very good, though to others I concur; it gets rather repetitive after a while. Maybe it doesn't need one track per level, but at least more than one for the entire game. The background also becomes uninteresting over time; perhaps the game could be split into sections with one background and one track per section. Maybe the music could even be based around the backgrounds. The art is also very nice. The medal designs are cute. I think there should have been more than one color for the bears navel for the bonus characters. The pink bear could definitely have had pink and purple as it's colors. I'm not as sure about the other ones. Maybe green and blue for the green bear, and white and grey for the black bear.
Oh, before I finish, here's one tip for level 17. If you get in the right spot, you can pass right in between the saw blades! Just wait for the saws to come down and then jump and fly through them. This'll give you more time to get to the top. It won't help with bonus modes, though it may make it easier to complete without checkpoints.