Yup that's a phone holder, everything goes through an app, although it can be controlled by hand or by the app. Pro and cons, go pro for me at least is very poor sound quality, no video display as far as i know, but is obviously lighter/smaller than the Osmo, not sure of the Go pro video capabilities, is it 4k?
Osmo has quite a lot of features such as 180 and 360 degree picture, slo motion video capture along with time lapse, can be used in 4k video format or you can reduce it to 1080, video can be edited within the app and also has inbuilt wifi