The temperature sensors work great for showing temperatures in different rooms. You can tell it to use one of the sensors instead of the thermostat. But if you have the thermostat set to something like 72 for example, and one of the other sensors happens to go up to 80, the thermostat will do absolutely nothing about it unless you manually tell it to use that sensor instead, or you schedule it to use that sensor. And you can only schedule in 4 blocks. 7AM-11AM, 11AM-4PM, 4PM-9PM and 9PM-7AM.
That's it. If your needs don't fit into those exact time blocks, you're SOL. There's no way to add more granularity or change the time blocks at all.
My biggest gripe is that you can't set it up to run the fans if there's a big difference in temperature. If I have the thermostat set to cool to 72, it's 68 in the hallway at the thermostat, but it's 75 in my master bedroom, JUST RUN THE FAN!
If any sensor varies more than X degrees from the main sensor, run the fan.
How hard would that be to add that feature?
When people come to my house, they see the fancy thermostat and comment on how cool it is, but then I say, "Yeah it looks cool but it's pointless. It doesn't do anything that a regular thermostat can't do."
Imagine how many more units would sell if people actually liked their Google thermostats and had good things to say when people ask about them.
All the fancy design, technology, software, processing power, extra sensors, internet access with weather information... And this thing can't even keep a house comfortable.
The only thing the nest thermostat is good for is setting a temperature schedule, and you can do that with almost any other thermostat.
