Damn clicky!
Yeah, I found the game somewhat unresponsive when I would click and try to "draw" my line sometimes, with trouble especially nearer to to the bottom of the screen. If I can't get the control I want, how can the rest of the game function properly?
Answer: It can't.
Nothing wrong with the game idea, but the poor control just plain ruined it for me. I couldn't go on for more than 5 minutes. Too frustrating!