The book has room for the parts the film cuts
Adaptations compress. Audiobooks restore subplots, minor characters, and the narrator's voice. Frankenstein, The Picture of Dorian Gray, and The Time Machine all gain from the slower pace.
Listen to the original language when you can
A public-domain translation is not always the best translation, but it is often free and historically interesting. Check the source page for the edition being read.
Use a text companion
Project Gutenberg links let you read a passage when the audio is unclear. That is especially useful for older vocabulary, dialect, and poetry.
Accept the performance
A volunteer recording is an interpretation, not a studio product. Give a chapter or two before deciding. If the narration does not work for you, try another version or a paid edition.