Before 8 months xiaomi have launched note 5 pro with Snapdragon 636, dual camera, 4000mah battery and with new 18: 9 aspext ratio screen. But this note 6 pro has just few minor changes. The nite 6 pro also comes with Snapdragon 636, dual rear camera and 4000mah battery. Only the changes are there is notch and there are dual camers on the front. Performance wise it is all same. The dual front facing camera is quite good. The notch is too big like the iphone x.
It is not a upgarde. May be they have kept name as note 5 pro plus. If you have redmi note 4 or 5 or the pro version no need to upgrade in my frank opionion. Yes you can upgrade if you note 3 or the older version of that.