Yes, it works great! The Nest Thermostat has a motion sensor in it that helps detect when you are home and turn the thermostat down accordingly to save you energy. You can also manually set the thermostat to away from the thermostat or from your smart phone, you don't really need to do this though because the Nest will automatically figure out that you are gone and adjust your temperature settings to save you energy and money.  On the app it lets you know that you have been saving energy while away with a logo of a house and a man walking out the door as shown in the screenshot below. With new upgrades to the app the nest also uses your GPS position to help make the home/away mode more accurate, nest has a more detailed description of the feature on their website.