The Android 5.0 Lollipop update is being pushed out over-the-air (OTA) and users should see a notification when it is available for them. For checking manually, users should go to Settings > About phone > Software update or use the Sony PC Companion app.
Unfortunately, Sony this time around did not provide a changelog for the Android 5.0 Lollipop update.
Going by the previous changelog for the Xperia Z3 and Xperia Z3 Compact last month, these devices should also get Google's Material Design interface (Lollipop-style notifications, and lock screen with fully customisable settings); Android Lollipop's multi-user profiles and guest mode features; improved storage control and customisation options to easily move applications from internal memory to SD card, and more.
Earlier this month, the company rolled out the Android 5.0 Lollipop update for the Xperia Z2 and Xperia Z2 Tablet. The update according to Sony is being rolled out in phases and might take some time to reach all handsets.