A lot of people that I've talked to loved this book and hated this movie. Like so many people I talked to, I loved this book, but I didn't hate the movie. Sometimes I think we want the movie to line up so perfectly with the book that we are let down when parts of the book are left out entirely or changed around to fit in an approximate two-hour format.
We forget that movies are unto themselves an art as well. Stephen King hated Stanley Kubrick's adaptation of The Shining, for example, but several film-goers would have to disagree on that one.
Let's first look as to what makes The Glass Castle such a must-read. First off, journalist and protagonist Jeannette Walls writes her unbelievable nonfiction account of growing up in a dysfunctional, vagabond and poverty-stricken family almost as if it were written like it's a fictional story. The facts aren't cold and hard, like statistics from a textbook, but woven beautifully through dialogue and character development. Jeannette goes from adoring her alcoholic, dream-obsessed father to loathing him. She shows us the setting in her writing. Instead of telling us that she lived in poverty, she wrote, "We needed at least a bucket [of coal] to keep a fire going for one evening. So while we made occasional coal collecting-expeditions, we used mostly wood. We couldn't afford wood anymore than we could afford coal, and Dad wasn't around to chop and split any, which meant it was up to us kids to gather dead branches and logs from the forest."
In those three sentences, Walls depicts the horrid way of life the Walls' children endured in their time in Welch, WV. It also showed how the children took over as the adults in the family by this time in the story with their father not around and no mention of their mother.
There were a number of great, detailed parts in the book that were cut in the movie that probably would have added more weight to the Walls' story. Instead, the film decided to elaborate on the split timeline perspective, and it added some material in Walls' present-day life with her fiancé David (Max Greenfield) to flush it out. The scene where Jeannette and David were invited over to Jeannette's parents' new squatter home in New York City I found somewhat annoying. It didn't so much bother me that it didn't take place in the book, but that it didn't seem necessary to the movie. I get the point where you want to show that Rex is still there for his daughter by saying she's not happy, but dedicating an entire scene to it when they could have used time elsewhere to focus more on their horrible upbringing seemed a disappointment to me.
That being said, Woody Harrelson saved that movie in a lot of ways. If you watch The Glass Castle and read it, the way Woody portrays Rex is spot on. He's a man with a good soul somewhere in there, but his strange idealistic, dreamer ways get tossed around like a hurricane when he drinks. As an outsider looking in, Brie Larson did not do that bad of an acting job playing Jeannette, but in this viewer's mind, the acting went downhill from there. The mom wasn't bad, but she could have been better had the script called to round out her character more like it had in the story.
One of the reasons so many people also had trouble with this movie, I believe, is because they made the dad look like the good guy. While you could argue that is certainly not true, as they did leave in the famous scene where he pawns Jeannette off to the pool player for sex, they also ended the movie with him handing the money over to Jeannette to help her pay for her college and left us grieving his death.
For those that read The Glass Castle, their mother was just as much the bad parent as the father. In a heart-breaking scene while the kids are starving in Welch, Jeannette notices that her mom is getting heavier. When her brother Brian yanks the covers back from her bed, he notices huge family-sized Hershey chocolate bars. "She'd already eaten half of it," Jeannette wrote. But these details were left out of the movie. When Rex threw the family cat out of the window early in the film, the mother sided with her husband and said that "Cats don't like to travel."
Entire characters were scratched, such as the schoolchildren and teachers in Welch that constantly poked fun at the Walls' children. The entire book where the Walls' lived in Phoenix and Battle Mountain were deleted in the film as well. Even so, the scenes the movie did pick were done fairly well. The hot dog scene and the corresponding conflict at the hospital matched up almost perfectly with the text.
I would recommend both the movie and the book, but like always, I would read the book first. Nine times out of ten, the book is better.