Given that I currently use as my main mobile a Windows Phone and the announcements that they are doing something around this area come (should be detailed at Build), I'd like this.
I live alone, I have a gas and electric bill of £800 pa, often I'm not home, I'll work late, end up in another country that night etc. Having something that lets me switch off remotely the heating would be useful to a point. But I only have the heating on for maybe 5 months a year.
What would be useful, is some software that realised I was heading home, automatically turning it on. That realised there is no way I'd be home within 30 min, so delayed heating going on. Without me interacting with it.
As for control of the temp, well, as mentioned thermostatic valves do a great job of that.
I just want remote On / Off timer functionality. £250 is far beyond what I'd consider reasonable for that.
I'd sooner have an array of Zigbee sensors for the temp, a controller for the solenoid and something to bridge it to TCP/IP land.
This strikes me as not only ugly (you wouldn't notice the current thermostat) but pointlessly over engineered in one aspect, whilst ignoring the most important one. If you have to remember to interact with the app, it won't work. I could save the odd £2 or £3 if I remembered to flick a switch before leaving home on a morning.