I received 6.0 update fairly soon after release. Battery consumption is better, as are a few other minor features. I have one VERY big complaint. The new App Permissions has been nothing but a piece of garbage for me. Two specific issues, with Google apps, best explain the problem.
1. When I added my first calendar event to Google Calendar I denied access to Location services. I've been unable to turn it back on as I get the wonderful
endless loop (Screen overlay detected, go to Draw over other apps and Calendar is not displayed). No matter which app I "turn off screen overlay for" allows me to re-enable location services for Google Calendar.
2. When I try and open a *.Doc file with Google Docs I get "Allow Docs to access photos, media and files on your device?" and again I get into this maddening endless loop where I "Screen overlay detected" and when follow link to "Draw over other apps" there is no Google Docs app listed, nor any other app listed that I can "turn off the screen overlay from Settings > Apps".
Very frustrating. I've even call Nexus 5 help to see if there is some way to gracefully revert back to Lollipop. Yes I know I can image my phone but I'm not keen on that approach.
If I could uninstall the apps it might reset permissions and let me do what I want. As it is I'm now installed 3rd party apps because Google's products are becoming a real pain.