This week I got the notification that I can update my note 4 to Marshmallow. The upgrade itself ran without a hitch. I would day my phone feels a bit more responsive than before. All in all it seems the biggest changes are under the hood. A couple of ico s were updates like the icons for the phone and messaging app.
I only have one problem so far. The fingerprint sensor seems to not be available all the time when the screen is locked. Often I have to unlock with my password. Nothing happens when I seipw my finger over the sensor. Not even the message I should go slower or faster. It sometimes works so I know the sensor works in general.
I already had started into the recovery system and wiped the phones cache. The only other option I have is to do a factory reset.
I never had problems like this with my nexus. So I might be going back or maybe a Phone based on cynagen mod.
For now it’s not too big of an issue.
I wish you well