I thought it was about 100 pages. Either way it was the reading equivalent of beating a dead horse over and over again. The repetition of the same point wanted me to gouge my eyes out.
I thought the first two movies followed the novel well. However, character development was insufficient for viewers who hadn't read the book.
For example, the scene in Part I where Dagny, upon meeting Francisco at a hotel/restaurant, throws a glass of wine in his face. Without reading the book, you would have no context.