Re: Nah
I installed a Nest this winter, one of the new ones with the bigger display and better motion detection. It works brilliantly. Ergonomically, it can work just like a traditional rotary thermostat, with the benefit that when the dial lights up you see the target temperature as well as the actual current temperature. The display is lovely. And when I enter the house or wave at it, it lights up to show the current time. These things aren't going to save your life, but anyone who likes gadgets will like a Nest.
Where it kills a traditional thermostat is in its learning capability, ease of setup, and environmental awareness. It learns your routines and the characteristics of your heating setup. So, for example, if I want my living room to be at 21°C at 6pm, Nest uses learned behaviour to engage a pre-heating mode prior to 6pm. How it does it depends on the (known) outside current and future temperature, the weather, and the thermal response to heating commands. It will deactivate ahead of time as the radiators keep pumping out heat. If you have a house full of windows, it can even take the heating effect of the sun into account. That's some pretty sophisticated control that just gets on with things in the background.
Does it save money? Yes, without a doubt. I don't spend my life buzzing around a thermostat, but what I do look at is the monthly heating report it sends me. In addition to applying just as much heating as is actually needed, there have clearly been many times when it's detected an empty house and automatically gone into Away mode.
Top gadget, in my opinion.