One thing is that its sort of hard to manually control. There is no real "fan-only" setting, for example. You end up working around the software a lot, to trick it into things.
Lately, its been worse. Its performing uncommanded actions. You set it to manual, click over to the air conditioner (which is still "unplugged" so will not engage) and if you wait a bit you can see it go "nope, you need heat." The little heat-mode icon lights up, and then the wavy lines that mean its making heat light up. Go to the basement, and yup, the heater is on. On a 76° day. One other hint, the temp display has a tendency to say "LO" instead of a number.
So, I finally give up with shorting leads and beating it with a screwdriver, and call the tech support line. Turns out LO means off scale low. The tiny, stupid computer in the thermostat thinks that its freezing cold. But its not, its just a bad temp sensor. Apparently, it feeds signal directly as a resistive signal, and 0° is about 0 volts.
Okay, its not the computer's fault. Its the designers. While its nice it says (cryptically) off-scale low, instead of a falsely low temperature when it gets a zero voltage response, who decided that the thermostat is smarter than the user? I am requesting "cooling" mode, so why switch to heat mode all by itself? Or, how about a spurious data sensor? It seems to disregard the 95% of the time it gets valid temperatures in order to fire some emergency recovery mode if it gets ANY zero-voltage temp gauge readings. This is poor design, making me sweat and wield a screwdriver needlessly.