Triple trouble: why book trilogies are better than film | Books | The Guardian

The study's author, statistics graduate student Kaylin Walker, took a range of book and film trilogies, and analysed their reviews on Goodreads and IMDb. "Movie trilogies get worse, losing favour with each film, while book trilogies secure higher ratings for book two and maintain them for book three," she writes.

Walker speculates as to why this might be: "It could be that book content is better. Authors have the opportunity to lay out the full arc from the start, resulting in a more cohesive story, while movie trilogies are often constructed quickly following box-office success, resulting in third-act disasters like The Matrix Revolutions or slapdash profit grabs such as Legally Blondes."