Before I start my actual review, I need to mention that this is my first smartphone. I've been refusing to buy one for many years now, as I had no need of it. Contrary to that I've been using ASUS Android tablets for 2 years now. Before buying the xperia, I was looking for a device to replace my Asus TF300 Tablet and it was then that I stumbled upon the Z ultra.
The xperia Z ultra is for me both a tablet and a phone replacement. It works amazingly in both worlds. The size of the device is perfect. I can use for long hours without getting tired, it is very light and feels really good and firm in my grip. The screen is really good. I expected to be worse after having read a number of negative reviews on it related to its viewing angles, but its quality is excellent in my eyes.
I never thought that an android device can be so performant. Perhaps this is not the best comparison ever, but chrome on this device is faster than Chrome on my i7 macbook pro. This tells quite alot. Switching apps is seamless and for the 3 days that I am using this phone now, I never had a glitch. Battery performance although quite bad for a phone I'd say, it's still better than all tablets that I have played with.
I had read lots of complaints about the camera. Personally I didn't care much for it. All I need to do with the rear camera, is the occasional scan or use the front camera for call conference. And they both work fine. If you plan to use the phone as a camera phone, look somewhere else cause you will really be disappointed.
Being waterproof is really a strong feature of the phone. I've used in the bath and out in the rain with no problems, nor glitches in the touch interface which surprised me.
I highly recommend this device and I also recommend buying the dk30 charger-dockstation and the sbh52 handset along with it. They both complement this device very nicely.