Much better than average old B-Movie, in the Crime/Detective genre. Movies like this are a guilty pleasure. There's just something about a good old Black and White mystery. Quite a number of funny moments, like when the Mayor overhears Tracy telling Tess something on the phone, or the reactions of Tess to the brunette who's going into "protective custody" at Tracy's place. A number of elements in this film were later used in the modern remake of Dick Tracy, with Warren Beatty and Madonna. (An underrated guilty pleasure) One example is the kid riding on the bumper of the bad guy's car.
Sure, it's a little hokey in places, but it's from the 40's. I recommend it.