Since months after launching the Xperia Z2, Sony is once again gracing us with a new flagship in the form of the Sony Xperia Z3. The Xperia Z3 maybe just a slight upgrade over its predecessor, but the company has clearly focussed on what matters.
The Xperia Z3 comes with a screen brightness and processing power that rival or surpass those of the direct competitors, while its pretty unibody glass chassis is made even thinner, still keeping the high waterproof rating.
If you are coming from the Xperia Z1, the newest Xperia is a worthy upgrade. However as a Xperia Z2 user you will have to consider if it is worth spending so much money for a bit better outdoor visibility, and a more balanced camera.
source - PhoneArena