The app works fine at its intended purpose.
There are no obvious controls, so I don't really feel in control of it. EG. I always have to experiment to get it to save the video, though when it does it's really simple, and I'm not sure how I'd save only the audio...
I'm sure with regular use I'd learn my way around it, but currently I'd welcome some more UI.
An annoyance is that it is not obvious where saved videos are stored - I always have to search the file system for *.mp4 to find my file.