Its biggest features seem to be WiFi, though that's just another way to do things manually for the most part, and its learning ability. The thing is, setting up a detailed 7 day schedule (that works) is pretty trivial on any programmable thermostat. For me anyway (probably you too). I know it's not for a lot of the general population.
That's enough for me!
I have a touchscreen thermostat with 7-day programming of four daily time periods (night, morning, day, evening). It's very easy to
understand how to program the thing, but it's a huge PITA to actually
do it. And it even has a battery so you can remove the control unit from the wall while you program it. But the interface is still awful and no fun to use.
I'll be happy to put a Nest in my next home (I don't plan to be in this one long enough to justify it).