I have tried several programmable thermostats over the years and by far this as the easiest to install, connect to my wireless and program. I have it running on a two wire heat only system with a 24 volt plugin transformer. Other than a little effort to run the 24 volt wire in the wall it has worked extremely well.
I bought this thermostat to replace my 10 year older one. I will say this was a great buy. It was easy to install and I love the fact that I can operate it anywhere from my iPhone.
I have installed and setup 3 of the Honeywell WiFi 9000 thermostats. Two for our daughters homes and one in mine. They are easy to install with good instructions and easy to setup. WiFi works great for remote access from my phone. Nice to know while you're away if something goes wrong at home. Highly recommend. PS, Honeywell support is very good also.
Overall it is great to use and it has synced well with my system. Although one minor complication is that when I or anyone in the household tries to use it it takes a few attempts for the screen to click. In other words it doesnt really work our fingertips. However, other than that this works perfectly.