Just finished watching The Maltese Falcon again after many many years.
I've read The Maltese Falcon three or four times over the past few years, partly because its a good book with a good yarn, but mostly to see what works and what doesn't work in a novel, even a genre novel like the Falcon.
The biggest flaw in Hammett's writing is that he doesn't understand women and doesn't pretend to either. His women are often hysterical, in the old sense of the term, and too clever by half: most of the women in his novels cannot make plans, follow plans, or know what a plan is. Exceptions include Nora, in The Thin Man, and perhaps Janet Henry in The Glass Key.
This flaw is exceptionally obvious in The Maltese Falcon. There are moments in the story when I just want to slap Brigid O’Shaughnessy silly. Oh well.
There are also scenes that are either extraneous or are put together in too haphazard a way.
The best Hammett novel, and apparently the one he appreciated the most, is The Glass Key.