[kstrauser]

> The form factor is almost the right one for an e-reader.

It truly is. It fits perfectly in one hand without stretching uncomfortably, so I can hold it for longer than any reading session I've had without making my hand get stiff. While holding it in the normal way, my thumb naturally rests on one of the side buttons, which I've mapped to "next page".

If I were to hold out my hand, and someone put an X4 in it, I wouldn't have to move a muscle and it'd be in the right position for me to read for hours with just the periodic button tap.

Everyone's different, of course. It's guaranteed to be too big or too small for others, and that's cool. For me it feels like someone custom designed it based on a model of my hand.