Sony Xperia Z Ultra gets unofficial Android 5.0 Lollipop update
If you want something really big with phone functions, the Sony’s 6.4-inch Xperia Z Ultra should be suitable for your life. It brings you a beautiful design, HD display, better camera and a nice range of Sony’s features. Future, the Google Play Edition of phone has already received the Android 5.0 Lollipop update officially. And the original edition will have this update hopefully soon. But third party developers have already managed to port the update unofficially for those, who cannot wait for official tricks.
There is an AOSP Lollipop-based custom ROM available for the phone you can try. It is still in alpha stages, so you can experience many bugs. But I have noticed the developer is trying to iron out bugs and I hope the developer will make it bug-less soon. As far, there are three things reportedly not working for, the video playback, signal indicator is broken when connected to LTE(very rare but exists) and GPS.
If you are excited to go unofficial, make sure you have unlocked the bootloader of device and installed a custom recovery. Then download and flash the system.img, userdata.img, boot.img, ROM zip package, and gapps via fastboot and recovery mode. For more information and downloads about this Xperia Z Ultra Lollipop update, check this XDA thread.