Genius Report has scored a pre-production Sony Ericsson XPERIA X1 and has put together a quick review of this first Windows Mobile powered device from the company; and it looks like it's all thumbs up.
In fact, it seems like BGR can't stop praising all of its features, and the build quality is meant to be second to none. The screen is also meant to be amazing and easy to read despite it's fairly high resolution at 800x480 pixels, but the font size can easily be adjusted to make it more readable.
The call quality is meant to be excellent as well and they love all the features of the device. However, there are a couple of flies in the ointment: first up, the built-in speaker quality isn't that great, and secondly, the keyboard isn't meant to be all that great, as it lacks any kind of feedback as it's almost flush with the casing.
You can find the full, if somewhat short, review here