As stated in other reviews, the physical buttons dont quite line up properly to the icons that control different parameters. Its somewhat workable but extremely finicky. You need to hit the buttons with a specific strength and timing for them to work. Also a flaw is if during playback of your video, if you do not let the entire file play through before trying to exit...you will essentially eliminate the option of getting back to the main shooting screen. This requires taking the phone out of the case for a fix.
Also, on my iPhone 6s Plus...the slow motion setting defaults to 720 at 240fps instead of the 1080 at 120fps that I have set in my Settings. There should be a choice between the two or the Watershot app should default to the System prefs.
Given that the housing costs a pretty penny AND they charge you $2 for the app...it should have been more polished for its release. Please fix!
dvsterk about Watershot for iPhone, v1.6.14