Dahl passed away in 1990 ... did it take this long? Maybe his family, or estate was -- as did Suess' for the Grinch movie with Carrey.
I think most of the new movie is truer to the book. The difficulty comes in that it is a children's book, very short, very quick read. Anyone who does a screen adaptation needs to add things to it. The book could easily be done in a 30 minute animate show for TV (an hour at tops, if you stick enough commercials in).
The original added all the school scenes in -- which only served to provide a cameo for a British actor and highlight Charlie's poverty (which I think was sufficiently highlighted in this movie). The new movie adds the dimension of Willy's dad, which is appropriate for the way in which the character was developed for this adaptation -- is further highlights Charlie as the hero. It's not Willy Wonka saving a family from poverty, it's Charlie teaching a lesson on the importance of family.