I wrote about WeMo when it was first announced, but now I've spent about a week living with one, and I have some additional observations.
WeMo is a Wi-Fi based power outlet that you can control remotely, over the Internet, using an iOS device. There's also a motion detecting trigger, but I don't have one of those.
My conclusion after this trial period is that the WeMo has some serious flaws, and even if they're fixed by Belkin, I'm lukewarm about its capabilities.
First off, let's discuss the design and software flaws. A new WeMo switch, when first plugged in, broadcasts its own Wi-Fi network. To configure the switch, you join this network using an iOS device, then open the WeMo app. From there, you configure the WeMo to join your household Wi-Fi. Sounds good, but that's when I hit my first stumbling block. The WeMo app only shows the first 5 Wi-Fi networks it finds. In my house, twice that many networks are available (I have a lot of neighbors) and my network didn't make the top-five cutoff. I did get the WeMo configured by manually entering my network's SSID, but for many users this would have been a big roadblock.
After I configured the switch, I moved it to the location where I wanted to use it. Big mistake because unplugging the switch causes it to forget its configuration. This is even more inconvenient then it sounds, believe it or not, because the configuration is also dumped when you apply a software update or have to reset the switch when it becomes unresponsive. The WeMo app does remember the info the switch needs, but you have to jump through the hoops every time.
In the one week that I've owned the switch, I've had to reset it three times. It just drops off the network and can't be controlled at all. Until Belkin fixes this, you simply can't rely on WeMo for when you're away from home. (And I assure you, my Wi-Fi network is strong and reliable, the problem is with the WeMo.)
A cruel trick of the reset problem is that the switch can get so confused it starts broadcasting its own Wi-Fi network again. I hadn't noticed this had happened and I was quite puzzled when my iPhone stopped being able to reach the Internet. It had remembered the network from before and auto-joined it when it re-appeared. I recommend you click the "Forget This Network" button in Settings > Wi-Fi after you've configured the WeMo.
So if Belkin fixes the reliability problems, is the WeMo switch worth considering? Maybe. I'm having difficulty imagining a scenario where it's essential. Being able to turn on a lamp from across the Internet is not automation, it's remote control. And when would you need to do that? (And be aware that you can only use it with things that are controllable by turning the power on or off at the outlet.)
In order to get any kind of automation, you need to use the IFTTT web service. it's a great service, but you're limited to one WeMo device per channel, and you're limited by the triggers and simple logic that the service supports. It's an interesting partnership between Belkin and IFTTT. I hope it continues to grow and flourish.
The WeMo does offer a set of "rules" (which should be called "schedules") so you can tediously set it up to turn on and off at defined times. That's a lot more useful, but it doesn't offer any randomization, so the only way it's better than a mechanical timer is that you can update the schedule remotely. That's a win for WeMo, for certain, but only if you need that capability.
There's a lot of promise in WeMo, but in addition to driving the price down, Belkin has got to fix its reliabllity. Until then, sadly, it's just a fun toy.
Update July 2013: After many, many updates WeMo devices are now much more stable. Some people are still reporting problems with Wi-Fi networks with multiple access points, but for me WeMo is now rock solid and reliable, and has been for several months now. Yay!