This one star is for keeping me addicted enough to want to finish this game (did it), and for the funny characters and ideas. The missing 4 stars are for commiting almost every level design and game play mistake possible.
Level 3: Almost at the end of the level (taking the shortcut), you have to fall into the unknown, and have to be lucky to not miss the brick. To have a fair chance, you must memorize where that brick is. A no-go for skill games. This happened in too many levels
I'd like to point out what I didn't like, being specific for each level, but you don't let me pause the game. Another minus point. The next things come off my head.
The balloon which floats to the left was a little bit unfair to find, but that was still okay. The bad part was that sometimes it would be stuck for a short time at the narrow passage, without any reason. Non-deterministic pauses in a skill and speed based game.
No easy way to restart the whole game. I figured out that I could do it by Q, then SPACE, but when the time was up, I had to use the mouse. No quick restart possible. Once it even lead me to restart the whole game shortly before I reached the exit, because the Game Over screen gave me a feeling of being blocked.
At one level a balloon floated up and down though another narrow passage, but it also floated just a little bit above the level where Santa ran. You would miss the balloon by just one or two pixels, without being able to notice it beforehand, effectively dying.
Lastly, in the last level, you had to jump out of the car not too early, and not too late, just before reaching the final exit. This is guessing at a pixel level.
Another frustrating design was that you couldn't restart just one level, and the time when you entered it. I get that this is intentional, so it shouldn't weigh into the rating. Still, this fact makes almost every remark I made even worse.