This answer contains spoilers… (view spoiler)[Nothing at all like the book. The admittedly underdeveloped telepathic plot in the book is boiled down to “Eddie” aka Edmund, being good with animals which was his twin’s role in the book except in the movie the twin becomes a younger brother and the oldest, Osbert, is left out. The six year time jump with Daisy returning is also skipped, Isaac now a younger sibling is killed when all the sibs survive in the book. Book Daisy is not restrained and dragged away after passing up achance to go home. Basically, they butchered the book for the movie. I was really disappointed. (hide spoiler)]
Alec It was a really good adaptation, they change/delete some characters of the book but the plot just keeps being the same, you gotta watch it! totally loved it.
Paige The general theme and emotional experience are well portrayed in the movie however I think some of the characters absence or trade outs (a few characters were "smushed" together to create a 'new' character for the movie) had to happen to make the movie make sense for the time allotted. And overall I don't think it hurt the plot. It actually made it engaging and fresh compared to the book. Not to say the book isn't fresh, but it added to it by changing it rather than being an exact repeat of the book on the silver screen. I can't say I enjoy the book over the movie or vice versa.
Lara To be honest the book it quite like the movie but they do change somethings and don't go to far into why she is in England. Though for me i liked the movie more than the book (which isn't my usual opinion). Sariose Ronan has to be one of my favourite actresses and i definitely think you should watch the movie, after reading the book of course.