- I really like that it's a combination sensor. To combine heat, light, and motion into one sensor alone is pretty impressive. I know the price seems pretty steep, but I haven't seen a sensor that does those three things alone for less than $75, and this is also a smoke/CO sensor, which doesn't exist for any other HA systems for some reason.
Clearly, they're doing a lot of their engineering with an eye toward the future. The original Nest thermostat had an 802.15.4 antenna, and it was unused. Now, it's used to integrate with these smoke detectors.