I could think of harder ones. That one took me and a friend about a week to finish. It was a bit tougher than most. Though most people should read the instruction manual. *IF* I remember correctly it told how to do the continue in there. At that point it is just a matter of leaving the thing on and just chipping away at the levels.
Also as the levels go on it goes from 'damn this is hard' to 'I am going to beat the nintendo in with a hammer'.