My perspective on all this:

1. I've not read the book, but Chaos Walking looks like a last splutter of a certain subgenre of high concept dystopian YA storytelling that began with The Hunger Games (which I very much enjoyed - especially the novels), and gradually became less interesting with the likes of The Maze Runner (pretty good) to Divergent (indifferent), and so on down the line. Obviously I'll reserve judgement until I see the film or read the book with Chaos Walking.

2. As a writer of fiction, I never consider watching a "bad" film (or reading a "bad" novel) a waste of time. Indeed, it is probably more important to study bad storytelling than good, as the study of failure is illuminating and humbling. Learn from what doesn't work, so you can learn what does. However, I can appreciate how watching rubbish films would be a waste of time for anyone else, unless you really are a dyed in the wool film buff. I regard myself as one, because I think a film buff is defined not by how many great films they've seen, but how many terrible films they've seen (Attack of the Killer Tomatoes anyone?).

3. Thirdly and most emphatically, I don't subscribe to the notion that the novel is automatically better than the film. Here's an article I wrote exploring adaptation to film, with examples of films that are better and worse than their source material. Jaws and The Godfather for example are both far, far better films than they are books.