I had the honor to play with a preproduction model when I was @ FOSDEM. It looks and feels pretty good - much more "precious" than I had expected by looking at the photos.
As a phone, it just works - with a good sound.
As a PDA, it's just cool - the landscape resolution gets some time to get used to, but the UI has been designed to take this into account.
The keyboard is very good for that size - feels a bit like on a Psion Revo. Display very bright and fairly readable in sunlight. Speed ok - about the same as on a clamshell Zaurus.
The OS felt rock solid, there's a recent kernel 2.6 underneath and ROAD patched the guts out of Qtopia 2.x to make it work
To my knowledge, we will be able to write applications for it. On the preproduction I already spotted some Opie apps
In short, it's recommended and will be my first Linux phone.
(No, I couldn't keep the device )