William K. Howard was given the task of turning a popular radio serial into a movie, and succeeded. A carefully-written script that actually paid attention to the way cases are tried was the first step. Some great support, particularly Skeets Gallegher and the always fascinating Zasu Pitts helps. A restless camera helps keep up speed, and some interesting sets -- particularly the nightclub set -- make this a fine movie, even if the leads, who became lovers more than twenty years later, had no memory of working together on this one.
I wish to call your attention, if you ever have the chance to see this movie -- it is very rare and the one print I saw was a 16 mm. print, blurry as you would expect -- to the swish cuts. A swish cut is when the camera starts to pan away, then the illusion of high speed movement starts and when the camera slows down it is panning into a new shot -- maybe a quarter second elapses. It adds tremendous excitement to a sequence and Howard uses a lot of them here.
Unhappily, a lot of editing techniques for shot changes were on their ways out. By about 1935, Hollywood had settled on the now-standard techniques, except for a few movies which attempt to evoke the older movies. A loss to film grammar, but what can we do about it now, except to enjoy these techniques when we see them?
May 20 2010: I just noticed a modern use of the swish cut: any Doctor Who fan out there should take a look at Season 5 Episode 4 for the use of one, four minutes into the proceedings.