Has reliability been addressed?
The big problem with these has been the reliability. Have they replaced the FETs with a relay? I doubt it if the profile is smaller. You don't want your thermostat dying when it's -40 out and you're away from home. (And, hopefully Nest has learned not to push software updates mid-winter! Most of the world isn't the Bay Area weather-wise.)
Also, regarding energy savings, I don't think they are comparing it to even the most basic programable thermostat out there, which I'd guess would get you to like 80% to 90% of what the Nest can accomplish over a basic el-cheapo thermostat with one setting and a big over-shoot, etc.