I followed the web address Looney mentioned above and found a review on that dashcam forum with samples. Looking at the daytime samples, they're no better than any other 1080P dashcam in my opinion. Not surprising since the limiting factor is the resolution plus bit rate. 11mbs at H265 is only around 24mbs at H264 from memory. Hardly groundbreaking bit rates. Also, for daytime, several manufacturers have either 1440P or 4K resolution cameras available. There are also cameras with higher bit rates using H264. As for night, the videos look quite good from the mix, if a little noisy in some places. However, the night performance alone would not persuade me to take this over a superior daytime camera as 90%+ of my driving is done in the day.
The built in memory on the Mix would be a worry as any wear or other issue in the memory and it's a new camera not solely a new SD card.
Think it probably has it's uses for those who drive mainly at night eg overnight couriers / delivery drivers etc, but the real breakthrough is going to come from a low light 4K camera with STARVIS or similar sensitivity as then you'd get both the daytime resolution and low light performance. Just my 2 cents.