The Xperia Z was launched in March 2013. It has a 5″ 1080p display, featuring an incredibly high pixel density of 441 ppi. It is powered by a 1.5 GHz quad-core Qualcomm Snapdragon S4 Pro processor, Adreno 320 GPU. The Xperia Z also features 2 GB of RAM, 16 GB of internal storage, which is expandable up to 32GB. It comes with a 13.1MP primary camera. Xperia Z is also water and dust resistant.
Android 4.4 KitKat was launched recently with many new features. Sony is yet to announce when Xperia Z will get the official update. However, Xperia Z users can get a taste of KitKat via the AOSP custom ROM due to the efforts of XDA member pabx. The ROM is quite stable for day to day use but it might have some bugs.