Xperia Z Ultra users began receiving 14.1.B.1.510 updates for their devices, that should be done through Sony's PC Companion software. All you need to do is plug into the Xperia Z Ultra computer, turn on the PC
Companion and proceed to check for updates.
The upgrade is similar to what was discussed in Exquisite article in late August, you can refer here. Basically once this upgrade brings the "X-Reality for Mobile", along with a new font and if observant, you may also recognize the change in color of the machine.