what i liked- the ever infamous 'dental plan/lisa needs braces' scene, homer wondering if burns is coming onto him, the union song lisa and the plant workers sing, the ending with lisa getting braces, etc.
great episode. a review can't mention how many humorous parts this episode had. pretty much every gag works so well and the plot is great, too. definitely not only one of the best of the season (if not the best), but also one of the best of the series as a whole. A+ episode, definitely