Forget about renders of Samsung Galaxy Note III: it's rumored to be smallish 5.5", possibly not powered by Qualcomm's Snapdragon 800 (=underpowered) and blissfully avid water sucker as they all Galaxies are.
Forget about Samsung Galaxy Mega 6.3 inch underpowered and heavily overpriced phablet: it's a joke. Some Chinese fake Note II can outperform it for a half the price.
Here comes the new king of phablets: Sony Xperia Z Ultra. Here are some specs (as per Android Central, plus some additions and refinements):
Qualcomm's quad core Snapdragon 800 2.2 GHz with Adreno 330 is not just a beast, it's a top of the line SoC, equal or better than that nVidia Tegra 4 chip which powers nothing as of today.
1920x1080 FHD IPS Triluminos display offers a feature called X-Reality better demoed here:
This X-Reality mode deserves more thorough testing, but as demoed it can bring in a lots of improvements not only to color, contrast and details rendering in video playback, but to static image renditions as well.
Waterproofing and dust resistance of IP55 rating means Z Ultra withstands dust, moisture, water sprays. Rating IP58 implies Z can dive to up to 5 feet water depths up to 30 minutes. Eat it, Galaxies! (or should I say: Drink it?)
Super Hard Coat ASF cover of touch panel also deserves more testing and demoing, but as per Sony's own description, together with having a screen protecting features it also adds this "pencil-sensing" feature:
The Xperia Z Ultra is the ideal business partner thanks to the super responsiveLooks like needle-sharp pencils are out, but as long as squishy capacitive styli can be thrown out, it's a great feature for note taking and even drawing. "Super Hard Coat" moniker is supposed to state that this coat resists to marks left by relatively "soft" pencil and "soft" touch of metal pen. So, with this phablet you can write and sketch with any pencil and selected stylus or pen (capacitive stylus or metal pen with tip diameter over 1mm). Nothing is said about palm rejection though, so Note II has some breathing space left still.
screen with handwriting recognition which is compatible with any pencil and
selected stylus or pen (capacitive stylus or metal pen with tip diameter over
1mm). You can even write notes or sketches during calls so you’ll always be ready
capture your ideas as they happen. The easy-toggle keyboard makes it ideal for
one-handed input and multi-tasking, with small apps to help you improve
productivity so you don’t lose time browsing between windows.
Self-healing scratches on that Super Hard Coat are also remain to be seen and believed. 6.44 inches of very thin screen in very thin frame also looks like so much more chances to shatter or develop cracks by relatively "light" drops. Scratch resistant feature won't also help if the phone lands flat on screen (or glassy back) on some sort of tile. Think of screen replacement works that may cost in excess of $300.
However, if you're in the market for a combo of prime 7 inch tablet and prime phone, this device may easily serve as both.
(to be updated)