My first impression of the “presence’ sensor on the thermostat (presumably when not using HomeKit) is that it seems like an unreliable way to determine if anyone is home. From what I’ve seen, thermostats in homes with a single HVAC/thermostat combo aren’t always installed in a high traffic area. In my own home the thermostat is more likely to sense someone when we are on our way to the inside garage door to leave the house.
On HomeKit, the Adaptive Temperature doesn’t look much different than scheduling capabilities and geofencing that have been available for years on “smart” thermostats, and don’t require everyone in the home to be in Apple’s ecosystem.
The Clean Energy Guidance feature seems next to useless for a thermostat, IMHO, although that probably depends on where you live. Mid-August where I live, when it’s sunny, 36c/97f, 98% humidity, wind speed 0 outside for hours, I need my home to be comfortable and shifting operation based on grid load, generation fuel cost, or anything else is not going to cut it anyway. It makes sense for other things, like EV charging, just not home thermostats.