If you want just simple record video at decent quality XIAOMI YII with basic feature is good.
But if you want to record video with full control over the shutter speed, ISO sensitivity and other feature to create fantastic videos and photo GoPro HERO 4.
If you want to buy GoPro just because its cool don't waste money on it because full potential of GoPro only can be unlocked if you really know how to use it by "tuning and manual handling".  Get a XIAOMI YII if you want less headache and less setup.

XIAOMI YII = Out of box ready to record video. So if you're not thinkering around with image setup, shutter management and in budget this one is great value.


GOPRO HERO 4 = Professional video recording with total video/image control for quality video/photography generating RAW file.  Great camera for post video/image editing works on PRO TUNE raw file.

So can't compare between orange and apple both seems to cater different purposes.
Remember the size of of MEGA PIXEL doesn't justify the camera quality level.  Its the internal CMOS sensors light sensitivity that count and the "Bit Rate" quality it produce. Quality over quantity.
Here are my snapshots on HERO 4 which i able to control the ISO, shutter speed, sharpness and other special effect: