These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
For hadn't Leslie, even in Terabithia, tried to push back the walls of his mind and make him see beyond to the shining world—huge and terrible and beautiful and very fragile? (Handle with care—everything—even the predators.)
Now it was time for him to move out. She wasn't there, so he must go for both of them. It was up to him to pay back to the world in beauty and caring what Leslie had loaned him in vision and strength.
It Was His Sled: Leslie dies. Spoilered because it's not as well known as, say Darth VaderbeingLuke's father, but since it is one of the most discussed things about the story, it's hard to avoid hearing about it whenever the book or movie is brought up.
Jerkass Woobie: Janice turns out to be one. At the end of the film, it's implied she and Jesse may become friends.
Moe: Maybelle. Just ... Maybelle. This is even lampshaded by Josh Hutcherson and Anna Sophia Robb in their commentary, the former of whom calls her "just the cutest kid ever".
Narm: In the 80's film version, the sadness is ruined by the awful acting on Jesse's actor's part.
The "You lie!" line is particularly laughable. Watch it here.
Paranoia Fuel: There's always a chance someone who is close to you could die in a freak accident.
Values Dissonance: In the book, Jess's mother is worried about his best friend being female. Because it means he might be gay.
The film on the other hand, Jess seems to get odd looks from his family when they meet Leslie; however, it seems to be that they're surprised he might have a girlfriend.
What an Idiot: Maybelle, you're a sweetie and all, but if you find a ring of keys lying on the floor of the greenhouse, don't you think you oughtta tell your parents?