The WM4201 is a unit about that looks like a candy-bar mobile phone (complete with Sony-Ericssonesque joystick above the keypad), decked out in iPod White (which is the new Consumer Electronics Black). Or at least it looks like a mobile phone in photographs; the first thing one notices when one unpacks it is that it is considerably larger than an ordinary GSM mobile (or at least one with an equivalent number of keys):
Getting started with the phone is straightforward; let it charge for a while, and then turn it on and let it find a network. (The instructions advise to let it charge for 8 hours before using it. I was somewhat impatient and switched it on an hour or two into its charging; this does not seem to have affected battery life or performance.) It can do WEP and WPA, so locked networks are OK; however, it doesn't have a web browser, so you're out of luck at access points that require web-based authentication. It then logs into Skype, fetches your contact list and balance, and is ready. It also gets the current time from the internet, though can take a few minutes to do so; so if your phone is telling you that it's 00:02 on January 1, 2000, there's no need to manually change this. Which is just as well, as the date-setting user interface is somewhat counter-intuitive.
WM4201, next to a Nokia 6230i, for purposes of comparison
As for making and receiving calls: the quality is pretty much standard Skype quality, i.e., good enough save for the occasional choppiness and echo. It only does voice calling as well; there is no way to send or receive text messages on it. Perhaps this will arrive in a future version of the firmware?
As this phone is a 1.0 product (220.127.116.11, it says), there are still some rough edges. For example, sometimes when it loses the wireless network, it crashes and becomes unresponsive, requiring you to remove and replace the battery to reset it. (The manufacturer seems to have neglected to provide the usual paperclip reset switch.) This only happens when it's running off battery power; leaving it plugged into a USB cable seems to make the problem go away. Also, on one network I tested it with, the phone kept losing the network connection every few minutes, though only when not making or receiving calls. Hopefully these issues will be fixed in the future.
All in all, I'm quite happy with the phone. It allows me to be reachable on Skype and make and receive phone calls without being near a powerful headset-equipped PC. It is usable as is, though there is room for improvement.
One question I have been wondering about: what exactly is the Edge-Core WM4201? The information page of the firmware reveals that it is implemented using TrollTech's toolkit (presumably Qtopia), which means that it's probably not a Windows CE device (after all, one wouldn't pay royalties to Microsoft and then avoid using their technologies). I suspect it runs on either Linux or some embedded system like QNX. The phone has a USB port on the bottom, though, disappointingly, there is no evidence of the data lines of this being connected to anything; connecting it to a computer reveals no new devices plugged in. It seems that the USB port is just used as a relatively standard way of feeding 5 volts to the device. The phone appears to be firmware upgradeable, though it does this by itself checking for updates on the internet.
I don't know what URL it pings to check for new firmware; I wonder whether it pings an Edge-Core URL for a version of the firmware specific to Edge-Core hardware, or a skype.com URL for upgrades to any WiFi Skype phones. I have seen photographs of other Skype phones, and they look similar, both in layout of buttons and the user interface. Could it be that Skype handed manufacturers a standard hardware platform and just makes a release of their software for this? If so, the differences between rival models would be limited to things outside of the reference design, such as quality of screens/keyboards/speakers and charging solutions.