Well, in my opinion the game is not fun enough. As you said as you go through levels it gets kind of boring, well that's not what you want from a game, I don't think you're being hard on it, I actually think "I'll be crazy for saying this" but the game deserves it a little bit, I'm just saying. As you also say @pusen there are some levels that get tiresome and end up being boring, and well one comes out annoyed from the level and may be from the game as well. What we always look for in a game is that it amuses and entertains us.
Do you agree with my rant?
If it was good I found it very interesting and well, it also gave me the opportunity to say some things about this game here in the comments section.