I have quite the same feeling.
I have an 11" notebook, where the keyboard starts to be wide enough to be usable comfortably for long periods.
I found the 9" eeePC too small to type comfortably with fingers.
On the other side of the scale, a 4.3" PhotonQ phone with hardware keyboard is quite comfortable with 2 thumbs, for reasonably long periods. It is a way better input system than the touchscreen for things that can't be auto-corrected, like passwords, IP addresses, code, or anything that needs constant switching between caps, numbers and symbols. Not to forget the arrows to quickly correct mistakes.
In the middle, a 7" keyboard seems too big to use with 2 thumbs, and too small to put fingers on it ? And same problem with the on screen keyboard : too big for single hand use on the move.
Device looks good, but it looks like I'm not the target for it. Still waiting for the e7 or n950 form factor to come back...