While the former movie is vastly superior, The Glass Key is undeniably entertaining. Alan Ladd is no match for the charisma and voice of Humphrey Bogart, and at 5' 5"" he is seemingly miscast as a tough guy. Fortunately, he gets by much more by guile than strength.
To one degree or another, most detective stories are male fantasies. The reader or viewer unconsciously puts himself in the lead role, where he is surrounded by seductive femme fatales and stupid villains to be bested. The formula is clear enough that Raymond Chandler allegedly wrote a detective novel in a single weekend, which if memory serves put him in the Guiness Book of World Records.
One has to recognize the weaknesses of the genre to fully appreciate its strengths. The characters are all stereotyped, with the exception of Jeff (William Bendix), who plays a curious combination of friendliness and brutality. From many other films, you've already met the confident political boss (Brian Donlevy), his wiseguy partner (Alan Ladd), the small-time but ambitious gangster (Joseph Calleia), the hottie sister (Bonita Granville) who is lovesick for a worthless gambler (Richard Denning), and of course the languid, honey-dripping, but dangerous young beauty (Veronica Lake).
Among the lesser performances, Arthur Loft as a newspaper publisher stands out because he is such a bad actor. One imagines that his character shoots himself not because the story demands it, but because the director lost patience with his overheated delivery.
A recurrent theme in the movie is that the characters of Ladd and Lake (they were leads in seven films together) are secretly in love with each other. Ladd supposedly remains hands off out of loyalty to Donlevy, who has given her an ostentatious ring. However, Ladd's alleged passion for Lake does not stop him from seducing both a voluptuous nurse and the cowardly publisher's solicitous wife.
Lake, meanwhile, is engaged to Donlevy and bats her lovely eyes at
Ladd, even though she believes that they teamed to murder her brother and
cover up the crime. But then, consistency of character and clarity of
motivation are secondary to action and intrigue in detective potboilers.