After releasing Android 5.0 for the Xperia Z3 and Xperia Z3 Compact just yesterday. Sony has started pushing out the update to the Xperia Z3 Tablet Compact and the Xperia Z2 Tablet. Sony is reportedly pushing out the update to all variants, both WiFi and LTE models as well. The firmware is 23.1.A.0.690 that is being pushed out to both tablets. At the time of writing this, the update is only available in the Nordic region. However we should see it hitting other regions in the coming days, provided that this OTA goes fine in the Nordic Region.
The model numbers being updated are the SGP611, SGP612 and the SGP621 for the Xperia Z3 Tablet Compact. With the SGP511, SGP521 and SGP512 being updated on the Xperia Z2 Tablet side. Those are both the WiFi and the unlocked LTE models. Not the Xperia Z2 Tablet that is available from Verizon. We likely still have a bit to wait on that one to be available, as carriers - at least here in the US - like to take their time in testing these updates. To be sure there's nothing wrong with them before pushing them out.
We got a chance to check out Sony's take on Lollipop back at Mobile World Congress earlier this month. They kept the update mostly stock Android, or AOSP, with a few changes to the colors. For example the sliders are not that blue/green color we have on the Nexus 6, but instead it's orange. Which I think stands out a bit more. Also the settings are in Blue and white. Instead of a dark blue color for the heading on the Nexus 6. Of course, you still have all of Sony's improvements or enhancements with their Xperia skin, but it's not a bad update at least on the Xperia Z4 and Xperia M4 Aqua.
For the carrier models of the Xperia Z3, Xperia Z3 Compact, Xperia Z3 Tablet Compact and the Xperia Z2, we should be seeing those start to push out over the next few weeks. We're hoping Sony did a great job with the update so that carriers don't find any bugs that need to be fixed, while they are testing the update.