I think my main complaint with this book is that it is dishonest. It's fiction, of course, but I feel it's presented to the reader under false pretenses. It is presented as the story of Linda's torment as told by Jill, a reluctant participant in the bullying.
But Jill is not a reluctant participant. She didn't start it, but she was quite happy to go along with ringleader Wendy's schemes, and she never expressed any kind of remorse or reluctance, even to herself. She very obliquely mentions Linda to her mother, not naming her specifically but observing that some people let others just walk all over them. I got the idea (all this came about when I read this as an adult; when I first read it in fourth grade I didn't pick up on all this, it was just a story about a very mean bunch of kids) that we were supposed to think that Jill's conscience was hurting her but that she could not tell her mother the full story because she would then have to reveal her own bad behavior. But instead, throughout the book, I was struck by Jill's utter lack of conscience, about everything and not just Linda. The story starts out believably enough, with the overweight Linda giving an oral report about whales and Wendy, the smartest and most popular kid in the class, passing a note to Jill saying "Blubber is a good name for her." And just like that, the name sticks and Linda is Blubber from there on. She isn't the fattest kid in the class; two girls and a boy are fatter. Nor was she previously a target, apparently. It was just her unfortunate choice of animals to give a speech about that set things in motion.
The class, led by Wendy and her lackey Caroline, aren't content with just calling Linda Blubber for a few days. They devote much time and energy to making Linda's life miserable. They call her names, trip her, make her kis Wendy's shoe, force her to repeat that she is a smelly whale, and make her kiss a boy in the class, who is no happier about it than Linda is.
Throughout, Jill never comes up with any ideas herself, but she is always an enthusiastic player in Wendy's ugly little game. She relates the incidents emotionlessly and casually, as if they are simply an ordinary part of her school day.
Nor is Jill's antisocial behavior confined to school. She and her friend Tracy not only toilet-paper and Silly-String Linda's house on Halloween night, they also put rotten eggs (which they have been keeping hidden for a month; I smell premeditation here) in the mailbox of a neighbor who, although he is widely disliked, has never done anything against them personally.
On this same night, Jill reacts with disapproval when Wendy and Caroline brag that they have smashed six jack-o-lanterns, saying "that's not fair." She has a pretty skewed idea of what is fair.
The book just seems to miss the point it was supposedly created to make. Yes, bullying is wrong, but so what? Jill doesn't really grasp this even when the tables are turned and Wendy begins picking on her. And what caused Wendy to do this? Not Jill sticking up for Linda, as we are supposed to believe. Jill interupted Wendy's mock-trial of Linda by saying that Linda is entitled to a lawyer, an idea Wendy rejects. I get the distinct impression that Jill only insisted on Linda's right to a lawyer because she was tired of Wendy having all the ideas and wanted some of the spotlight for herself, and that her letting Linda out of the supply closet against Wendy's wishes was solely about raining on Wendy's parade and not about any compassion for Linda.
Jill is miserable once Wendy switches her attentions from Linda to her, but she never connects her own hurt with the hurt Linda must have felt. She doesn't get that she is reaping what she has sown.
And Linda? Linda is an unsympathetic victim, not because she is unpleasant but because she is totally devoid of personality. She seems to be a natural-born victim, and her passivness is creepy. But worse is her reaction when Wendy abruptly stops abusing her and begins abusing Jill. Rather than just ignoring Linda, Wendy somehow, in the space of a day or two, convinces Linda that they are best friends, even abandoning her loyal henchman Caroline.
Is Linda truly so stupid that she would so quickly forget the weeks of verbal and physical abuse and believe that Wendy was now her friend? For that matter, is Wendy really that good a manipulator? Honestly, Wendy puts me in mind of a hardened prison inmate who runs not only the other inmates but the guards as well. She was just too over the top to be realistic. Also not believable that her evident sociopathy was completely unknown to any of the teachers at school. In my experience, high achievers like Wendy didn't sink to her level; they might make nasty remarks or tell lies, but the ones who engaged in the kind of sustained, systematic mistreatment of others were not as socially sophisticated or academically successful as Wendy was.
The book's ending is unsatisfactory but plausible in that Linda is again left friendless and Jill is still not sorry for anything she has done. But in fiction, characters are supposed to change somehow, and the fact that neither Jill, nor Linda, nor Wendy changes makes the book feel like it was a completely wasted undertaking.