This film was beautifully done and usually coincided with the book. Of course there were many scenes from the book that couldn't be expressed in the course of 2 hours, however there were some major things in the movie that didn't coincide with the book at all.
(Spoilers ahead) The biggest part in the movie that didn't coincide with the book was that Henry didn't make amends with Catherine until he met her in Fullerton. In the book he is supposed to treat her especially gently just an hour after the incident in Mrs. Tilney's room.
Which leads me to my next point. The Mrs. Tilney's room scene was almost perfect, except that her portrait wasn't in her bedroom, but Eleanor's. Catherine sees it the second day she is at Northanger.
The second problem with that scene is more important. It is that Henry gets very angry with Catherine, when in the book he is merely reprimanding Catherine's fancies and is actually very kind to her. But of course she still feels awful and reacts much like she does in the movie.
Another large inconsistency was that Northanger looked exactly how Catherine imagined (Dark, dreary, gothic, horrid etc.), while in the book Catherine is a bit disappointed how modern the house is because it has been renovated. Indeed, the only thing she noticed that was still a bit gothic were the shapes of the windows.
Additionally, Catherine does not meet or see John Thorpe before he and James meet Catherine and Isabella in the street. And although it is possible that Isabella and Captain Tilney may have had an affair, that is never said, nor largely implied in the book. Also, Eleanor does not have a poor lover who becomes rich. The only thing that is ever mentioned about Eleanor’s love life is that she married a rich Viscount, enabling Henry to marry not-so-rich Catherine.
Other than these issues the movie did quite a well job of compacting the story. It may have been better in a series (Even a mini series) simply because it did not really capture all of the life, tension, and emotions of the book because all the time in the movie was brief. However it is definitely better than the 1987 Northanger Abbey!