This kept my attention for hours, continually replaying levels and trying different trajectories to see what kinds of insane behavior I could produce. The fact that the game rewards the player for the most improbable and ludicrous stunts possible makes it highly entertaining. The graphics and music were soothing in their simplicity and did not get old even after replaying a level dozens of times; which is good, because there's really no other way to play, especially on some of the later levels. Between that and the sheer length of the game, it's definitely not something to be completed in one sitting.
The downside of the core mechanics in play is that the rocket's behavior can be wildly different from one target pixel to the next, especially when some of the more advanced obstacles come into play. This leads to a long time spent retrying the same shot, searching for the exact pixel that will make the rocket do what you want. It can become mind-numbing, especially on the later levels where you do have to line up some of those perfect shots to clear the level with a high enough score. To some extent this is unavoidable with this type of gameplay, but it often seems exacerbated by the level design, which tends to amplify the effects of minute differences in a rocket's trajectory. Some kind of aiming aid might be helpful; at very least a line from the rocket to the cursor, so the player can see exactly what angle it's going to fly at.
Other than that, the only complaints I have concern the behavior of dialog boxes when restarting over and over. Specifically:
The instruction page that comes up at the beginning of the level begins to get annoying after restarting repeatedly. It's not really necessary to have a page come up on every level that says "get as many points as you can". It's particularly annoying if you manage to fire a rocket while the box is up and you can't see what you're pointing at. Additionally, I encountered a glitch where if I clicked too quickly to dismiss it, the text on it would blank instead. Clicking again would dismiss the dialog, but it still looked buggy.
Also, the fact that the menu won't open (to allow the player to restart) while a rocket is in the air detracted from the flow of the game. Especially if I've just set up a shot that I know is going to slowly bounce ten times and finally explode, I want to just restart and be done with it, not watch it go through the motions again. In fact, my suggestion would be to add a dedicated keybinding to restart the level.
It's still a good game, though, and I plan to come back and finish it eventually. But not now. I think it's given me carpal tunnel. :)