Conclusions: Umidigi Bison real world user.
Three issues:
1. When using camera flash, flash fires after photo taken, resulting in black photos.
[other people also report this issue: https://translate.google.com/translate?hl=en&sl=ru&u=https://4pda.ru/forum/index.php%3Fshowtopic%3D1009153&prev=search&pto=aue]
2. When connecting to wifi, mac address is not retained when reconnecting to the same wifi, even after changing the setting to retain.
[other people also report this:
https://translate.google.com/translate?hl=en&sl=ru&u=https://4pda.ru/forum/index.php%3Fshowtopic%3D1009153&prev=search&pto=aue
https://4pda.ru/forum/index.php?showtopic=1009153&st=900 ]
3. The phone is advertised as having two customisable buttons, but only one is.
[see https://community.umidigi.com/forum.php?mod=viewthread&tid=19520]
Haven't tested the claim of being water resistant yet by as the charging and headphone ports are open, it's likely the metal within will rust when used in salt water.