I got one. It’s the only GoPro I’ve used.
It’s great – the form factor is small and waterproof without a case (I used it for sailing videos to check my technique etc). Vid quality is good.
Drawbacks:
Built-in battery means that you have a ‘one shot’ charge which lasts approx 2 hrs. After that it’ll need a recharge before you can use it again (no popping out the battery and sliding a new one in)
No built-in screen means you use the app via your phone to make sure the framing is correct. Using the bluetooth/wifi means the battery life is reduced, but allows for remote control if the camera is at the top of the mast for instance.
Downloading vids using wifi is slooooooow. Better off buying a card reader to plug into your phone and extracting the card each time you want to downlaod the vids.
Think thats it.