The best of black-and-white films are such that the viewer forgets very quickly that there is no color. If truly good, it will impart a style and an atmosphere that color can't duplicate. By 1947, when this movie was made, there wasn't much that a major studio couldn't do superbly in B/W. All their talent has been transferred to this DVD.
The premise for this movie is indeed improbable, and the idea that someone would want to change into the Bogart time-worn face is laughable. However, the interplay between the Bogarts is electric, and she never looked any sexier. The San Francisco art deco buildings and scenery is an added bonus. Agnes Moorhead, certainly one of our most underrated radio and film actresses, was never better as the catty friend. As a variation of film noir, though, this is fun to watch and gets better with each viewing.