Both devices are having a minor makeover, as the update looks to address problems with the display as well as improving connectivity and camera performance.
This should aid the Japanese firm as they pin hopes on their Triluminous display to take on the likes of the Super AMOLED screens found in the Samsung Galaxy S4.
Intensive users should be satisfied, as battery life will also be boosted as part of the update. We commented that the Xperia Z1's battery "was easily good for a whole day of use and then some", but we all know you'd all like more life.
The love doesn't stop there, as anyone using Microsoft Exchange should also notice that their emails sync and download quicker.
But wait, there's more
There are also some device specific updates, with the Xperia Z1 gaining a camera update. The 20.7MP camera will gain better performance and smoother camera apps on Sony's Smart Social Camera platform.
As for the Xperia Z Ultra, touchscreen sensitivity has been adjusted. With a 6.44 inch screen, improved finger and stylus support will be a boon to many.
Both handsets launched with Android 4.2 Jelly Bean, with Sony saying the latest update addresses customer feedback.
No product launch is ever perfect, even Apple has had to launch updates soon after launch. Anybody remember the iOS7 lockscreen debacle?
As the update is now being pushed out by Sony, we hope to see it land on devices soon. As ever, this depends on the market and networks pushing the update themselves.