I have one. I like it, though I feel like it can do so much more than I use it for. Plus, the underlying system I have is older, so I feel like I have a high end stereo and using baling string for speaker wire, if that makes sense.
It's handy, though, and you can program the crap out of it easily (on your desktop). I've used the programmable theormostats for years now (I even put in a Honeywell for the other zone in my house) and feel like I've saved money with it, frankly.