I first read J. M. Barrie's novel while I was writing Dirty Little Secret, my epic Arrested Development fic. Those who read it will know that Gob's got strong opinions about Peter Pan, and the author's psychological issues about family. I do personally think the novel is a lot darker than the Disney animated film. For one thing, Barrie lists "murder" among the mundane things that kids keep in their crowded imaginations, and Peter Pan is described as rather selfish and sadistic in the book. He starves the Lost Boys so that they'll fit into the tree holes, and apparently he kills some boys now and then. He also forgets friends and enemies alike, especially after he kills them. He is much more callous and less heroic in the book than in the cartoon. Peter Pan lets people get into danger, and then saves them at the last minute to show off how clever he is. It's not because he actually knows about moral right and wrong. He can be quite a vicious kid, and Barrie comments often that the other children are cruel and thoughtless too, including the Darlings who blithely stay in Neverland for what seems like months, not worried at all about their parents. It's certainly much longer than the few nights that are depicted in the films.
Anyway, I recently bought a DVD of the 2003 live-action film and watched it. I enjoyed it, and it is mostly faithful to the book. Where it isn't faithful, it actually improves the story. For instance, Tiger Lily likes Wendy's brother John and kisses him, whereas in the book, she had a crush on Peter. (In fact every female character in the book seemed smitten with Peter Pan, who's just oblivious. Even Wendy's mother when she was a little girl might have loved Peter before, and she has a special kiss just for him.) That trend of every female adoring the immortal boy (who still has his baby teeth) felt disturbing to me after a while, especially in the epilogue where Peter continues to visit Wendy and starts taking her daughter and granddaughter away to be his "mother" in Neverland. Presumably he keeps using that family into eternity, and maybe he already used Wendy's ancestors before, but he forgot. Anyway I liked the departure from the book of having Tiger Lily appreciate John Darling instead. There's a cute scene where Tiger Lily's family sewed up the teddy bear and made John an honorary member of the tribe. It was much less offensive than the Indians stuff in the Disney movie, though still a little stereotypical. Also, the mermaids in the film are said to be sinister to everybody, without it being implied that they want to drown Wendy specifically just because they are jealous of her and want Peter for themselves. So that helps lessen Peter as the boy that every girl wants.
Another nice surprise in the movie is that Wendy's stories about Cinderella aren't just traditional fairy tales; she has Cinderella fighting pirates, and when they play, she joins her brothers in acting out the swashbuckling. Wendy also gets to do some swordfighting in Neverland, and Captain Hook asks her to become a pirate on the Jolly Roger, so Wendy says she'd like to be Redhanded Jill. In the book, Hook made the offer to Wendy's brother John instead, and he was the one who wanted to be Redhanded Jack the pirate. I think this change is good too, because it helps to emphasize Wendy's journey of temptation and trying to find her role in life. It shows that she dreams of an adventurous life, far different from what her aunt told her earlier, that she had to grow up and be a lady. The movie very much revolves around Wendy's coming of age, and Peter Pan's stagnant life as "a tragedy." He apparently longs for love, but he doesn't ever want to grow up and live the normal life that Wendy and her brothers will have in England. Even the Lost Boys choose to go live with the Darlings rather than stay on Neverland with Peter forever. Overall the movie is a good improvement on the book, though it still portrays the Darling children as spending a few days at most on Neverland.
I still think it's a dark book, and don't know why people think it's so wholesome and innocent. NBC is apparently going to do a Peter Pan musical next, but I don't know if I'll watch it. I might see it out of curiosity to wonder why British people love this book and character so much, despite the parts that seem unhealthy and totally inappropriate for kids.