I've been lucky enough to get to play with a Universal Pocket PC Phone, and I think I like it a lot. The screen on this thing is just gorgeous - it's VGA - which means that text is rendered so smooth it looks better than paper.
The size and weight of the Universal makes me think of my Velo 1 Handheld PC: the first Windows CE piece of hardware I owned. Windows CE v1.0, 4Mb of memory, 4 or 16 greyscales, built-in modem, weird expansion memory slot, and battery life of a few minutes - how I loved it. To constrast the Universal has a VGA colour screen, built-in WiFi and GPRS mobile phone, standard memory expansion and works all day.
The Universal VGA screen makes the eBook Reader application look great, but it also works very well with Remote Desktop Client (or, if you are occasionally naughty like me and stray from Microsoft from time to time), VNC. See the picture to see just how naughty I get.
Still - I do miss the sheer pocket-ability of the Smartphone. What is your favourite form-factor? What would be your IDEAL device?