When I see a film based on a novel, I like to read the novel to compare plots and execution. Most of the time the novel or story is fuller than the movie due to the short media time and the target audience. In this case the novel does have a better-developed plot and is more cohesive. The characters are more true to form and there is a real Rosewood/Rosebrien. However the book characters are more sinister and Dorothy is sleazy.
The film on the other hand, was modified to give a lighter approach. William Powell & Myrna Loy have a magic that brings the story to life even when they repeat the same words as in the book. However one of my favorite lines was the drunk that says "Which knee can I touch it?" This is the film that I will think of as the real "Thin Man" and Maureen O'Sullivan as this Dorothy is concerned about her father. Speaking about that, what is the Sullivan act?