Yi 4k action cam vs hero 4 black Image stabilization
Watching footage from the hero 4 black edition and the Yi 4k action cam, it's night and day. The IS doesn't take care of everything, but it eliminates around 90% of the shake.
Image quality so far has also been impressive. You don't have quite as much range as you do with protunes, but the baked-in image of the Yi still looks surprisingly good.
Text, image and video via elonedork