The controller is a nice design, however in most other departments the Mavic runs rings round it - especially being so small when folded.
Image quality will be better but there will be fish-eye effect to deal with.
I've alway felt action cameras are not that suitable for aerial video.
The GoPro and gimbal+grip is ridiculously heavy compared to the DJI cameras so everything else has to be much more substantial to carry it.

It is a sensible complete system if you already have the gopro though, and don't want to be too ambitious with the flying part.
The gimbal grip thing works well because gopro owners will know a major problem is trying to keep it steady when handheld. 

The advertising made me laugh with hikers and skiers trying to pretend the parachute-size backpack was incredibly compact, when a Mavic will literally go in a (big) pocket.