I was expecting great things from the YI, as it is getting quite popular review, but I was quite blown away with what you can get for $250. I mean, the YI 4K is half the price of the GoPro, which you would think will put it with the knockoffs bin. But no. It actually scored much higher than the HEro 4 on our tests.
Of course, different people care about different things, so score may vary a bit for you, but all and all, I think it was a very clear cut, and if you judge value for money, it really is a no brainer ( see our comparisson table below)