We recently installed a Nest thermostat into our hour and we love it. It works seamlessly with our iOS and android devices.
Being upfront, we have an Apple ecosystem in the house, iPads, iPods, and Apple TV. We have not taken the last step to a Mac as we have had a PC desktop or Laptop in the house for a long ,long, long time.
Secondarily we had someone who knew what they were doing it install it. It's not that I couldn't install it, it is just that it would be quieter and calmer in the house than if I did it. I guess if peace is necessary in your house have a professional install it.
Now why do we like it. Let me start by saying we upgraded to the Nest from a programmable thermostat which in itself was an upgrade from what came with the house. Unlike that unit, there is no programming or punching buttons as the Nest sets the schedule by learning your heating/cooling habits. Secondarily via your home wifi network it measures not only the inside temp but it also humidity, and movement. The latter is used to determine if anyone is home. If the house is empty it goes into the away mode which sets the temp to presets for either heating or cooling.
We also installed the nest app on our iPads.
When you tap on energy history you get the above bar graphs showing your energy usage of heating and cooling on a daily basis. You will also note the weather indications to the right of the bar.
All in all we are still learning about it, but so far it is worth our investment. Only time will tell if it lives up to its claim to reduce costs.
The only con, at least so far, is the cost it isn't cheap but nothing of value is.