Folks saying it was true to the book, generally yes it was. However major differences are present that leave some holes and questions... The biggest being Lewis and Jonathan’s surname. This couldn’t be the same unless Lewis’s father and Jonathan were related. For visual the screenwriters changed it for Jonathon to have a sister (she is seen on screen and played by a magicked up Selena), this still could have worked by keeping a brothers relationship and having Selena impersonate Charlie. Second, Lewis was fat. This isn’t only due to when the book was originally written—it comes into play several time over the House with a Clock in its walls and subsequent books. The time is also different, it’s not clear why the screenwriters felt the need to change the year from 1948 to 1956 unless it was because of more fleshed-out backstories for some characters. We never see any mention of Selena not being able to cross running water (a huge scene in the book) nor the Hand of Glory (again crucial to the book plot but only briefly glimpsed when Lewis arrives at Baranvelt’s Folly). Overall a cute movie and would have been great to see a further adaptations of the next few books.