This game is the most comfortable I've ever been giving 5/5. It's hard but never insurmountable. The platforming was precise but not pixel-perfect (and let's face it: most have us have been playing these enough that it's nothing we can't handle). Further, it was fair: the game tells you about the off-screen effects of your actions, the dangers follow predictable patterns, and everything random in the boss battle is telegraphed so you can react to it.
But most strikingly, this game was an immaculate example of game design principles that can make these action/puzzle platformers truly great. Each mechanic is introduced slowly and safely, then enhanced with increased risk, then presented in a thorough challenge that tests your abilities and understanding. Additionally, I found the rooms then closed with an extra challenge that forced me to rethink the mechanic in an entirely new way to solve a final challenge. Importantly, everything brought into the game was explored to its full extent.
In all honesty, this is what I want when I look for a multiplayer pong game, except for the speed of the paddles. If the "turbo" speed was the default, and if the computer had a maximum speed, it would be much more entertaining. That being said, I look forward to playing it with another human.
Honestly, if I were going to tweak it, I would increase both the frame rate and the frequency at which the changes to the tunnel are made and also slow it down a bit.
Note that if you walk off a platform, you can jump in the air. Use that technique if you find yourself having trouble making some of the jumps toward the end.
The level with the three trampolines -- I assume you mean level 9? Levels 6 and 7 also have three -- is not impossible. I spaced them out carefully. There is more than enough room.