[TetOn]

This was my take...the interface for turning it off is difficult to find because it was designed to be thus. The last thing most thermostat users want to do is to turn it off completely. Instead, they want to "turn it off" or "on" relative to local environmental conditions...and that's the dead-easy interface mentioned in the link: turning the big dial ring and having it respond both numerically and by color: I am going to get hotter or I am going to get colder. The click side of the interface is deliberately more obscure and meant for the administrator (for lack of a better term) and not the random temperature adjuster.

TFA seems to be complaining that it's too difficult to find a feature that most thermostats elide completely. Every other model I've owned in the past could only be turned off by unplugging, which requires un-mounting the entire thing or powering down the furnace (or similar).

[vonmoltke]

I have never owned a thermostat that did not have an "On/Fan/Off" switch. The only thermostats I have ever seen lacking those switches, besides the Nest, are the thermostats used in large central HVAC systems where the thermostat is actually controlling a local blower and air damper, not the actual system.

[titanomachy]

Not being able to turn off the device is a problem if it controls both AC and heating (not sure if the Nest does). What if you just want the room to be whatever temperature it is outside?

[IshKebab]

Nest only controls heating. If you want it unheated you just turn the temperature down.