NEST has rolled out a nice software update for their NEST thermostat that gives you a 10 day history of your energy usage, that you can drill into in order to graphically display some pretty granular information. Below, you can see the orange bands showing exactly when my furnace was running over the past four days. Here in Parker, it was in the mid eighties outside on Sunday, and then we had a 40 degree temperature drop on Monday, and a small snow storm on Tuesday. On Wednesday, we had increasing temperatures by mid-morning, into the afternoon. You can easily see the effect the weather had on the furnace usage over time. I think that is pretty neat!
Another improvement in this update is the ability for NEST to shut off your air conditioner a few minutes before you reach your target temperature, while still running the fan to distribute the chilled air in the system into the house.
I have had my NEST for nearly six months now, and I have been very happy with it. I installed it myself (which was easy), and I think it looks pretty cool. It has a motion sensor that lights up the display when you walk by (and also detects if nobody is at home). It uses your Wi-Fi connection to connect to the Internet for weather information and to send and receive usage and control information. There is a free Android application (and one for iPhone/iPad) that lets you monitor and control your NEST remotely. You can also use a browser to monitor and control it.