I got these to replace Radio Thermostats that are loosing their connectivity. The app is much clearer to use than the prior app. A pleasant surprise was how well the anticipation algorithm works with my steam boiler, adjusting the time to start recovering from nightly setback depending on the weather. 4 stars instead of 5 as I no longer can adjust the program from my laptop -- I have to use either my phone or the thermostat screen.
My T9s were a gift from my son who has a T10. It took a while to get it to work. Turned out the first one was faulty but the second one is working great. Waiting for a replacement.