There’s potential here, but it’s not ready for prime time – Vizzywig: Record & Edit Videos Review

It’s just not there yet. While it’s a novel idea to use the camera’s burst mode to string together images into a 4K video, the result is pretty much unusable (even on my iPhone 6). Applying a third-party motion filter to the video also doesn't fix the issue. Hopefully this will be fixed in a future update since it’d be terrific to just pull out my iPhone and quickly record 4K video.
Review by movieboy23 on Vizzywig: Record & Edit Videos.