The update worked fine without any* problems for me (regular Fairphone install without any mods).
It does feel more responsive.
*Problems:
- Had to install a new SMS app, which was already announced (tried QKSMS, seems fine)
- All my contacts and calendar infos are stored in my outlook.com exchange active sync account. When I now add this (as I did under Android 5) via “Exchange”, only the e-mails get synced (afterwards, it shows up as an IMAP account in the accounts list - this explains why only the mails are synced). I currently cannot access my contacts or calendar.
- Problem solved here: Outlook.com exchange active sync not working