Let me say right off the bat that at least for me, there were two things working in this film's favour even before I started it (as 2 nifty percent of my infamous Mill Creek 50-pack, 'Nightmare Worlds'): a) I love the old-time serials, a part a week at the theatres, each with a cliffhanger ending; and b) I'm a fan of Buster Crabbe, from seeing him previously both as Tarzan and in a Flash Gordon serial. Directors Beebe and Goodkind were masters at the format, and this is no exception (although since it's from the 30's, and with B-movie budgetary restrictions at that, I readily dismiss all negative comments from people complaining that for the 1950's, it's really crappy filmmaking--it's NOT from the 50's, but simply edited then into a feature-length film the company could then sell, most probably to television stations).
I enjoyed it, though I wish that instead of seeing this, I was watching the unedited, undiluted full serial that was originally made. I have read that the best and most exciting parts were edited out.