Sony has posted the required open-source kernel files of Sony Xperia Z1 and it is available for download from their developer website. The best thing I like about Sony is that, they never made their phones difficult to root. In addition to this, they allow developers to create custom ROMs.
Sony’s Xperia Z1 comes with high-quality imaging 20.1-megapixel camera, 1080p screen, powered by Snapdragon 800 processor, 2GB of RAM and comes with 16GB of storage (storage space extended by using MicroSD card). Sony Xperia Z1 comes with 3000mAh battery and the body uses waterproof aluminum. Sony Xperia Z1 glass designed with mid-mounted power button and physical camera shutter. Right now, there is no word on pricing yet and the phone is all about to go on sale worldwide later this month.[Source] Sony Mobile