So I took the plunge and updated my Lumia 925 to Windows 10 Mobile 10166. There's a few bugs here and there but overall I'm loving it. Things like better support for multiple identities, i.e. MS account and also Azure AD (Office 365) accounts and OneNote discovering notebooks nicely across both OneDrive and SharePoint online. Outlook is great, as are the other Office apps, and directly printing from Word to our IP printer with no set up required! Groove music is nice, and of course there's Edge. I connected a bluetooth mouse to it too, very cool how the phone adapts to mouse mode automatically and shows scroll bars, and allows text selection on Universal Apps etc. Just wish the phone had mirracast support so I could play with using it as a desktop :-)

One issue I'm having though that hopefully someone can help with. If I go to Settings --> Update and Security --> For developers it just crashes out and sends me back to the Start Screen. Anyone experienced this or know of a way to resovle? I have given my phone a reset to start fresh with no baggage since the upgrade.