Menu -> Settings -> About device -> Software update -> Update.Everything takes time, as long-term Android users will know only too well, but with Sony having gotten its house in order, many should begin to see the notification of the OTA. If you own one of the aforementioned devices and don't see anything, you can check by going to
There is, of course, the small matter of carrier intervention -- a process that can throw up delays at a drop of a hat. Thus, whether you see the over-the-air update will depend largely on which network operator you do business with, as well as your region.
As for the software itself, you get customization improvements, tweaks to the camera, better enterprise support, and all-new LinkedIn featurette. Additionally, there's SmartWear integration, which will let you use the now-much-cheaper Sony Smartwatch 3 as a remote shutter button for your device's camera.
Sony has also announced that the more antiquated Xperia Z1, Xperia Z1 Compact and Xperia Z Ultra will all be in receipt of Android Lollipop in the "coming weeks." After that, the Xperia T2 Ultra, Xperia C3, and original Xperia Z series will follow, before the Xperia M2 and Xperia M2 Aqua hop aboard thereafter.