This film follows the patterns and lands in what could be expected, which is sort of OK in comedy. It does have some amusing twists to it - especially the drastic mixture of past and present. The characters change places with their younger alter egos, like flashbacks but in present time scenes. I would say that this is how our memory works, making us jump in time subconsciously, as if we have forever that teen inside of us. Also, it adds a poetic quality to the film.
It's the most endearing with the main character, who interacts constantly with his teenage self, who tries desperately to make him more cool, and urges him to get out of his sheltered existence. Yes, how kindly would we be judged by ourselves in our teens, if they saw us now? To some extent, we can live with it, having other values than we did back then, but in other cases - well, well.
I would have loved to see this conflict explored and deepened - that between the adult person and the teenager he once was. Unfortunately, the film stays on the surface of it, probably in fear of darkening the comedy too much. But comedy thrives on darkness, not on light. Happy and well-adjusted people don't invite to laughter, but misery sure does - I think already Aristotle stated this, in what little remains of his thoughts on comedy.
Certainly, there is some misery in the film, but just as it is about to really grab us, then comes a smile with snow white teeth, or a joke to release the tension. It is irritating. So also, is the fact that the dialogue contains little worth listening to. The writers/directors have not penetrated the subject sufficiently, or they just don't think so much of it.
Still, there were several moments where I laughed out loud, and in between the film was kind of cute.