This review is a little complicated, but I urge you to read it before buying this product. Just a couple of notes before we get started: 1) This review looks at the cooling cycle of the device; I live in a very warm climate and have not tested the heating cycle. 2) This review covers TWO different Emerson Sensi units of the same make and model; when I first noticed this behavior I assumed it was a product defect and filed a warranty claim with the manufacturer, who sent me a replacement. The same behavior was noted in both units. Without getting into the woes of owning this thermostat (and there were many), I'll just present the finding: In order to control a/c runtimes, the Emerson Sensi's firmware artificially manipulates the device's temperature sensor. I have enclosed three different pictures. Each picture is of the Emerson Sensi (bottom right) and two different thermometers. The thermometer on the left has a clock, so you can see the 'time code' of each picture. The pictures were taken when the outdoor temperature was just about the same as the indoor temperature - around 76 degrees. 1) Picture #1 was taken at 9:18 am just when the a/c finished running and the unit turned off. Note the Sensi believes the room temperature is 73 degrees but the two thermometers show a temperature somewhere between 75 and 76 degrees. 2) Picture #2 was taken just 15 minutes later (9:33 am) shortly before the a/c started running again. Note the Sensi now believes the room temperature is 75 degrees (warmed 2 degrees in 15 minutes?) but the two thermometers show no temperature change whatsoever. Can you say impossible? 3) Picture #3 was taken some 40+ minutes after #2 (10:15 am) right after the a/c finished running its next cycle. Note the Sensi believes the room temperature is back to 73 degrees but the two thermometers show almost no change in temperature from previous pictures (the left thermometer is actually up 0.4 degrees). The three pictures capture a full a/c cycle - off to on and back to off. Somehow, some 'magical force' changed the Sensi's room temperature from 73 to 76, turned the unit on, ran for a few minutes and the temperature magically went back down to 73 and turned the unit off. All when two independent thermometers registered almost NO CHANGE in temperature during the full cycle. There can only be one inescapable conclusion: the Sensi's firmware is manipulating the device's temperature sensor in order to control when the a/c turns on and/or off - completely independent of the room's 'true' temperature. What this means is the thermostat will sometimes run your a/c too much - and at other times, not enough. I will post some 'heat of the day' pictures as time permits, but when it's very warm outside, the thermostat will turn off the a/c far before reaching the desired set temperature. You might think that's good - but it makes for a very warm house. Again, I have verified this same behavior with two independent thermometers. Oh - and one other thing: if you read the manufacturer's response to some of the comments for this product, you'll notice they post this canned message about the Sensi's 'tight' temperature control range of +/- 1 degree. See my pictures: if the variance from the set point is just 1 degrees (specification says it should be 1.2 degrees F for medium cooling cycle) - how is the Sensi's 'room temperature' 73 degrees when the set temperature is 76 degrees? I realize that Amazon has many different products to manage, but deceptive, misleading, or downright fake products need to be pulled from the shelves. Most of my observations were over a period of 60+ days (remember two different units), so it's highly unlikely I can get my money back.