Thankfully the writers decided against having mini-Jack stop aging, mentally and emotionally, at the age his body stopped at. Jack O'Neill as a teenager is something best left unexplored.
I loved the way the characters reacted to their CO being a pimple-faced kid. And the interactions between Amanda, Christopher, Michael, and Michael Welch were amazing. The comic timing was impeccible and the dramatic wasn't overwrought, which it ran the risk of being.
Other than the creepiness at the end where mini-Jack is checking out the high school girls (Jack's closer to fifty than fifteen; I don't care how old his body looks) this was, overall, a great episode.