I also have an Ecobee3. I had come from a 2nd gen Nest. I will agree with others and say that the remote sensors are really nice. I've always had multi floor houses whose temperature differentials (between up and down) would border on 10F. Obviously I could adjust the temperature on the Nest from bed, but I found toward the end of my ownership (middle/end '14) that the service would be down every now and then and I couldn't communicate with my Nest. I haven't experienced this with the Ecobee yet. Another positive you can quickly see the weather forecast from the thermostat, which is great for when you're about to leave the house and don't want to whip out your phone.
On the downside, the Ecobee doesn't "feel" as high quality. The touchscreen shows finger prints, it has a plasticy feel and you don't have that nice orange or blue background color indicating whether it's cooling or heating (not a big deal). It also doesn't have the schedule learning system, but to be honest I would usually adjust the temps manually throughout the day anyway. It also doesn't have the automatic fan function after the AC has run, sort of an afterrun fan which helped continue to cool the house without the AC on.
In the end I wanted to try something different and so far I think it's met/exceeded my expectations. Just hope you have a C wire when you install! :)
On the downside, the Ecobee doesn't "feel" as high quality. The touchscreen shows finger prints, it has a plasticy feel and you don't have that nice orange or blue background color indicating whether it's cooling or heating (not a big deal). It also doesn't have the schedule learning system, but to be honest I would usually adjust the temps manually throughout the day anyway. It also doesn't have the automatic fan function after the AC has run, sort of an afterrun fan which helped continue to cool the house without the AC on.
In the end I wanted to try something different and so far I think it's met/exceeded my expectations. Just hope you have a C wire when you install! :)