Funny I have radiant floor heating and it takes hours to change temp. Traditional thermostats also suck at getting it right they cut off heat when the setpoint is reached which do to the lag is far to late and it overshoots. Compare that to a IoT thermostat that can figure this out take outside conditions into account. Mind you radiant floor heating is generally wonderful with a nice ven warmth. Hell all that thermal mass means I lag hours behind in the summer as well.
IoT is a bad idea it's everybody's device going to the cloud and only working together if a deal is struck. I do want lots of sensors etc in my home controlled by a local box, maybe the box is pretty thin shifting things to the cloud maybe it's thick and does everything locally in a perfect works it's a hybrid. It gets weather forecasts, calendaring info, school closings, when my phone thinks I'll be home, current buy prices for electricity, etc but it generally uses local logic to make decisions.
For it to realy work well it needs more data, requiring grocery stores to publish all their prices including sales if they are to accept food stamps would mean near perfect information with that NGO's etc can make near perfect shopping lists. Expand out and your refrigerator knows what you have historical trending and thus can figure out your grocery list. Your thermostat can figure out if it's cheaper to run the heat pump or a ng boiler or electric hot water heater. Your sprinkler system can put off watering if rain is expected and not send the robot lawn mower out hell it can know if there is some town ordinance that says you can not water your lawn today (and still do so if the owner says to).
It's also little things, since you can get a decently powerful wifi enabled full ip stack microcontroller for under a couple bucks now. That means no clock ever blinking 12:00 as the sntp can provide it. It also means that pretty much every sensor etc can be networked and thus used. Is the humidity up in the kitchen says the stove, well the exhaust fan can turn on says the home controller.