I saw the movie and came away thinking that I you not not read the book it was hard to follow. Kind of like trying to listen to a conversation at another table. You might get the jist of where they are going...but you miss a ton of nuance.
Try it on audio.
If you set aside the time it is worth it. You will be adjusting your listening schedule to more, quite often.
I saw the movie 6 times while it was in the theaters. I would take friends or family members to go see it. Those who had never read the book said that they didn’t have any trouble following the story as depicted in the film. Some also got interested in reading the book after seeing the movie.
Yes, unfortunately, it's part 1 of a trilogy. At this point ONLY the folks who know the book will get it. It would be like expecting everyone to know the whole Star Wars story after part 4 was released. At that point, parts 1, 2, 3, 5 and 6 didn't exist.
At the end of part 4, all we knew was that we had seen an exciting, very cool movie, but we didn't have the complete story.
Technically speaking, we still don't have the complete story of Star Wars because the last trilogy in the series (at least, what Spielberg/Lucas originally described) hasn't been either filmed or released. And, we may never see the last three films. Spielberg/Lucas aren't sure that they want to do them.