The good cast is the main strength of this solid, rather unassuming film-noir. In particular, Peter Lorre is excellent in a supporting role, and Mickey Rooney strikes a good balance with the main character, who is sympathetic without being particularly likable. The story is interesting, and it holds your attention pretty well despite an occasional hole and some predictable developments.
Rooney's character narrates a cautionary tale of how a questionable decision or two, combined with some bad breaks, caused his life to spiral downhill (in keeping with the "Quicksand" image of the title). For it to work, the audience has to sympathize with the character even while cringing at some of his choices, and Rooney is successful in making this happen. Jeanne Cagney gets one of her larger roles as a disreputable woman who helps lead Rooney's character astray, while Barbara Bates is well-cast as his loyal girlfriend. Art Smith is good in a minor role.
Lorre is the one who stands out in the cast, though, playing the kind of crafty lowlife that he portrayed as well as or better than anyone else has before or since. He makes Nick, the arcade owner, shabby but menacing, clever but brutal, and it adds considerably both to the atmosphere and to the impact of the story.
The story works all right as long as you go along with it, and overlook an implausibility or two here and there. The cast does most of the work, but some of the settings also help out in establishing the atmosphere. The mechanic's shop and the dingy arcade, as well as the pier in the climactic scene, all form an appropriate background to the events of the story.
