It reminds me a bit of the animation used in some of the Universal Dracula films for the vampire/bat transformations.
It's a clever cost cutting measure, but not very effective for me personally. Even for a serial it's cheap. In a live action superman adaptation you should see a live action superman flying imo. The fact is Columbia didn't put as much money into their serials as Republic did and it shows.
I will say the animation is at least good animation.