Super cool. Mount on the nose of your board, top of a helmet , or handle bars, done.
The waterproofing looked a little if'y. Vague at best. Even though they snapped on the little goggle thing, they never actually showed any underwater shots.

I like the general concept.

Seems that this specific set up requires the cameras to be low on the horizon..

Wonder if they can do adjustable downward angled lenses that change angle as you increase altitude..
Or additionally or separately change focal length to accomplish something similar...

Not at all, it's essentially 360 view except for the dead zone at the bottom--or the top if you flip it over. Any angle of view is available in the viewer. I suspect some people will edit the resulting video to deliver the view they would have had if they held the camera or controlled a gimbal during the shooting, though many won't.

Waterproofing will be an issue. In theory it's IP58, but I doubt that they've really tested that fully. The goggles aren't for waterproofing, the camera is IP58 without them. The goggles correct for the refractive index of water.