From what I've read Hitchcock only did this film due to a contractual obligation, but I believe (I have zero proof of this) that Hitch was partially interested in turning the play into a film because nearly the entire movie takes place on a single set and he wanted to maybe use the experience as practice for his massive single set masterpiece he would make later that same year: REAR WINDOW. Don't quote me on that, it's just me thinking out loud.
Anyway, DMFM is a good film. It's nothing groundbreaking (even though some of the camerawork is very impressive), but it's good for a one time watch. One thing I did notice that impressed me was Grace Kelly's dresses change color as the film progressed and her situation became more dire. The first five pictures (after the poster) below show the progression. At first she is happy and her dress is crimson red, then a darker red, then white, gray and finally black.
Not the greatest Hitchcock film, but still a solid one that deserves to be seen.