Unfortunately, I’ve only had bad experiences.
With the Spirits it depends explicitly on the hardware revisions. As far as I know, there are 4 different revisions to the spirit. Gen 1. The most reliable generation.
Gen 2. completely inoperable. Were exchanged by Eurotronic free of charge. Exactly very flawed. Uncontrolled heating. Gen 3. thermostat hangs up.
Latest generation still a lot of problems.
Most of the problems arise with FLIRS. That makes them quick to react, but very prone to failure. It depends on how often and with which devices they are repeated. You can be lucky or you can be very unlucky. The same bugs are reported in the forums of the competition.
In any case, I would wait until apps support the Zigbee thermostats before buying.
