I have to admit that this is one of my favorite movies ...
First, there are the two plots unfolding; the grandfather and the almost adolescent grandson, and the story itself....
Then there is that main plot ... and like Rocky & Bullwinkle, with just enough pratfalls and simple humor for young children, enough angst and unrequited love for the teen crowd, and one liners and zingers so racy that for most kids it goes right over their head ....
A heck of a movie ....