MobileBurn has written up a pretty in-depth review of the Panasonic X800, which is Panasonic's latest foray into the realm of Symbian OS Smartphones. While they liked its fashion-forward appearance and the connectivity (Bluetooth, GPRS, etc) seemed okay, most of the other features seemed fairly lackluster. Some of the criticisms include a poor keypad backlight, unrefined user interface, slow startup, and an average VGA camera. So overall, it's probably one of the slimmer Smartphones out there, but it's not the most functional.
Review of Panasonic's Symbian OS X800 [MobileBurn]