Nest build quality is great, and they look nice, especially if you can paint the wall and not use the vanity plate. The internet functionality was clearly the focus and it does well there. Thats about it for the good though.
Its functionality is a bit wonky especially when using motion considering the thermostat often can't see you. The reliability is questionable, I do controls and automation for work and have replaced 2-3 now all having the same problem (orange wire not energizing for cooling on a heat pump) and no these were all installed months apart by different contractors. The UI meh, I would describe it as tedious and vague. I installed a humidifier on a hvac system that was using a nest and it gave me water droplets icons to set the humidifier level, that's like having a moon and sun to set the temperature (not sure if that has changed). And its picky about what equipment it will work on, certain zoning systems can't handle one, let alone more due to its power consumption (its not "a lot" but compared to a basic thermostat it does).
The Nest Protect (CO/Smoke detector). Average at best, there is a lot worse out there but the Protect is nearing the price of a low level co monitor. The difference is a low level monitor will go off around 4-5 ppm of CO in seconds while I believe the Protect qualifies for the British standards institution spec which is 30 ppm CO the alarm will sound after 120 minutes, 100 ppm CO 10-40 minutes (that is really pushing your luck).
I don't have experience with them but their IQ cam looks really good. I've been thinking about buying one just to compare to what I have now. But overall, Google can have Nest.
