People vlogging would probably prefer the ergonomics and weight of a phone over something more serious, so I wouldn't be surprised if this competes with the GoPro on functionality and image for 'walk and talk' people?

Guerrilla film-makers will probably love it - iPhones aren't really noticed and are allowed in plenty of places where serious cameras aren't.

I can also see it being useful for some specific commercial ad work, I've seen people specifically shoot on phones to get the relatable phone 'look' for specific shots.