I’d give Kon-Tiki a B for cinematic values and a B+ for historical interest. Seeing the movie made me want to read the book again and try to find the documentary made about the expedition that won the Academy Award in 1951.
The movie was based on Kon-Tiki: Across the Pacific in a Raft, one of the first books I remember reading. My father, who was not a sailor but a ship captain during WWII, recommended it to me, and I was enthralled by the story.
Here’s some info about the movie from the IMDb website.