[bartveld]

First impressions:
Very thin, too big to hold safely or comfortably with one hand for a long time. Capacitive screen as responsive (or unresponsive) as the H2O screen. With Natural Light at zero, it's whiter than the H2O. Natural Light can give it a softer hue, which is nice at all times. 10% brightness on the H2O is way darker than 10% on the One. Light is very evenly spread across the screen.
I find the automatic brightness rather fickle, jumping from one setting to another when moving the device a little. Also, way too bright. The help-text suggests some sort of learning ability, but I doubt that. A patch that works like Light Flow on an Android device would be nice.
The bigger screen is the asset I bought this one for and it is worth it. Flush screen is very nice (but I know that's a question under debate).
Automatic sync keeps being turned on again, even after a full shutdown. Very annoying.
Can't say anything about battery life yet.