Fridge Brilliance: According to this episode, Bart's favourite song (or at least one of them) is "Love Stinks". Considering how many relationships he's had over the series and how they have all ended, Negative Continuity or not, is it any surprise?
This episode becomes more depressing after many bullying-related murders and suicides hit the news, specifically what happened to Phoebe Prince.
An earlier episode, "The Joy of Sect", shows Springfield being outright cruel towards a football team for losing a championship match, even going as far as to attack the players. This also leads to Fridge Horror where it's possible that, had Bart not attempted suicide, the entire town might've murdered him for the same reason as the football players.
Heartwarming Moments: Despite this episode being hated for showing Springfield as cruel enough to drive a ten-year-old boy to suicide, the scene of Marge calling the town out for what they've done and arranging a new game to pick up Bart's shattered self-esteem is a bright spot in an otherwise pitch-black episode.
Also, there is LaBoot trying (and failing) to save Bart, even though he was very evil to the boy earlier in the episode.
Moral Event Horizon: The townspeople cruelly treat Bart, simply over losing a lousy baseball game and even after Bart tries to commit suicide they don't stop abusing him. Making things worse, when Homer tries to take Bart's side, they actually bully him into reconsidering. They at least apologize to Bart once Marge calls them out on their cruelty. Nonetheless, this is said to be one of the most mean-spirited moments of the series.
Never Live It Down: While they did apologize to Bart, many viewers see this as "too little, too late" and would never see any citizen of Springfield the same light ever again.
Nightmare Fuel: Just the fact that such a seemingly cheerful, quirky town like Springfield would do something so heinous as what they did to Bart alone counts as this, especially to a number of long-time Simpsons fans who saw the episode for the first time; Jeez...
The Scrappy: Joe LaBoot's hypocrisy when he learns that he's speaking with Bart, and then is completely evil towards him, has gained him a large Hatedom.
Some Anvils Need to Be Dropped: As much as some people hate this episode, it does show that publicly shaming someone over something minor can have an adverse effect on their psychological being.
Tear Jerker: Bart's entire ordeal, especially in light of recent events of kids being bullied and either driven to suicide or murdered over it.