I've had an ecobee 3 since November, and the UX has been very responsive and intuitive to me. My wife can use it well enough to set manual away and temperature overrides, which is pretty much all that you might need to do after you've set it up. The android and ios apps are nothing special, basically just a clone of the thermostat's UI itself, but they work. The web app is very good, and the graphs are very nice and useful, including the ability to export all data as a csv. I've never used a Nest so I don't know how it compares but I'm quite happy with the ecobee.