It wasn't hard, but it did ask a lot of questions that your average homeowner may or may not know. Do you have a humidifier on your furnace? A dehumidifier? How is the emergency heat configured? Is the fan DC or AC coupled? Questions like that. I self installed mine no problem, but I can see how people could be intimidated.
For what it is worth, I think the Nest has been generally worse than a dumber programmable thermostat, especially after Google took it over. The App only allows a single phone to be connected now which is a problem when both me and my wife want access. There is also no way to run the fans without switching it on heat or cool. The fans can also only run for a maximum of 12 hours before it needs manual intervention to restart. All of which are a problem if you have say a pellet stove providing heat in one part of the house and want to circulate the air to the rest of the house using the furnace fan. On my old thermostat I could even switch the fan to low speed mode when the heat pump wasn't running, which is something the Nest seems to have no concept of. There is an API, but it's all Googlefied and requires a subscription and kind of assumes you're already a full stack Google developer.
For what it is worth, I think the Nest has been generally worse than a dumber programmable thermostat, especially after Google took it over. The App only allows a single phone to be connected now which is a problem when both me and my wife want access. There is also no way to run the fans without switching it on heat or cool. The fans can also only run for a maximum of 12 hours before it needs manual intervention to restart. All of which are a problem if you have say a pellet stove providing heat in one part of the house and want to circulate the air to the rest of the house using the furnace fan. On my old thermostat I could even switch the fan to low speed mode when the heat pump wasn't running, which is something the Nest seems to have no concept of. There is an API, but it's all Googlefied and requires a subscription and kind of assumes you're already a full stack Google developer.