A coworker of mine bought the XDA II mini over the holiday break and is now using it as his primary phone. I have to say that it's pretty sweet in a lot of ways and really shows where the form factor for mobiles is heading. You can't really get a good perspective on the device by looking at a picture of it (more and more devices are like that), but once you hold it in your hand you can get a feel for its size and weight and see how nice it is.
First, let me say what I don't like: the fact that this is a PDA and not a smart phone. It's running "Microsoft Windows Mobile 2003 PocketPC Phone Edition Second Edition" which I really think is a hunk of junk. Not only do I object to pen based UIs on principle (one-handed operations should be primary on a handset), but in this case the screen is a lot smaller than a regular Pocket PC which makes aiming the stylus a real effort. Forget about using this thing on a bus, you have to be perfectly still (and not had any caffeine that day) to click a button on the screen. It's like threading a needle.
Okay, that said, I think the rest of device is pretty cool. Holding it your hand, the XDA II mini feels solid. It's a bit heavy - about the same weight as my old Nokia 7650 - but a lot slimmer, which makes it feel nice in your hand. It gives off that same vibe an iPod does. Solid. The thing it really needs is a little slide out keypad or mini-keyboard and it'd be perfect. I love all the hardware specs of the phone: the screen size, the memory, the processor speed, the Bluetooth support, normal headphone jack, and I really like the fact that it has an SD-IO port in it. Though 3G would be nice, being able to plug in a SD WiFi card is pretty damn handy. Really, the only thing it needs is to get rid of the pen based UI.
The screen is really what strikes you when you hold it. It just seems huge compared to a smart phone like my Nokia 6630. And I have to admit that I like that the latest Windows Mobile allows you to flop the screen horizontally (Nokia should learn from this). It's just a QVGA screen which I've already seen on several phones, but on this device the screen just looks really nice.
Now that I've said all this, it dawns on me that the reason I like this device so much is that it's a "candy bar" form factor, which I still prefer, but which the most of the world has already voted against. I think that we're going to see a lot more devices with this size screen pretty soon, but they'll probably be on the top part of a flip phone. I would have to assume that maybe a happy medium in the future will be like Nokia's 6260 flip/twist phone, but with a bigger screen on the top part.
Anyways, cool to see the evolution of these devices and to hold it in your hand. You can grok a device so much better when you get to fondle it.