I previously had a green BV6800 Pro from amazon.co.uk. It had water ingress issues so I ordered a replacement (this time yellow) which I received yesterday.
My first impression is the camera autofocus seems ok but not tested extensively. The microphone worked on the previous phone but was not very clear apart from in normal phone calls.
It seems the microphone is not working at all on this yellow unit, I have recorded a video of the phone recording a video of some tv noise. You can see from the video that the BV6800 Pro is recording strange noise. The video of the BV6800 Pro was recorded on a Galaxy S7 which you can refer to the sound for reference purposes. I have tried other apps such as the voice recorder but the result is the same. I've tried restarting the phone as well.
On the plus side this yellow one looks nicer IMHO and it arrived with the sim ejector "plectrum" this time, although I didn't need to use it but I know some others wanted one

I haven't tested the IP68 yet.
Here are the videos on dropbox. I may try to upload if the forum lets me.
https://www.dropbox.com/sh/g9rsa1blp2a3 ... irDIa?dl=0
I'm also not keen to return this phone as it came from Blackview direct via aliexpress (from china). It seems I can only use it as a games device for my kids but even they want to use the voice search on google play to find games e.g. "my little pony"
Best Regards
Adam