The Willcom D4 is a very good looking UMPC but is it that good in real life. Apparently judging the comments from Tech On, it's not.
(1) Short battery life (claimed: 1.5 hours, measured: about 1 hour)
(2) When not locked, it easily starts up even when something touches the screen by accident.
(3) Its surface quickly becomes dirty with fingerprints.
(4) The cooler fan is noisier than expected.
(5) You can't operate the D4 while wearing one of the standard-length straps available on the market.
(6) The location of the mouse button on the left makes it difficult to press when using the keyboard.
(7) The optional Bluetooth handset seems to be required to quickly answer incoming calls.
(8) It becomes so hot that your hands or your desk also get hot.
Let me say that if you read the article, the author got the D4 about the same day the iPhone 3G was released and like he says, he was expecting from a D4 to be a real competition to the Apple device. Sorry... but UMPC are far from being SmartPhones though I should admit that 1 hour of battery life is just ridiculous. Even 1.5 hours is really really bad.