I added a PIN to my Microsoft account.
If the machine goes to screensaver from inactivity, then the PIN will unlock it (if connected to the internet).
If I am offline though, or it wakes from sleep/reboots, then the PIN will give me the dialogue "You are offline. Please logon with the last password used on this device".
This wasn't the case in Win8.1. My PIN always unlocked, whether online or offline. (I connect via mobile phone tether which isn't automatic - I have to manually go online, so the machine never boots 'already online'.)
This is a little annoying, and wondered if there's a way round it (but not using local account as I do a lot of online stuff)