The “incest” aspect of Victor & Elizabeth’s relationship was actually edited out between the 1818 & the 1831 editions of the novel by Mary herself. In the original, they were cousins; in the latter, she was a foundling. The movie followed the latter course.
I found it to be the closest movie to the book up to that time (a TNT production almost a year earlier starring Patrick Bergin & Randy Quaid as Victor & Creature came close). Last year, however, Hallmark TV did a production with Alec Newman & Luke Goss as V&C, with Donald Sutherland as Captain Walton which was essentially THE book in movie form.
I liked the fate of Elizabeth in Branaugh’s version- I think Mary S would have approved.
The only other major differences between Branaugh’s version & the book- in the book, Henry Clerval is killed by the Creature after Victor refuses to make the bride & Victor is temporarily jailed for the murder (in Scotland btw), Victor’s father’s name is Alphonse & he is a local aristocrat, there is actually a middle brother named Ernest who does nothing in the book. And the book itself gives no details as to the Creation, tho Mary’s 1831 preface refers to a machine inducing the spark of life.