The Nest Thermostat is a learning thermostat that is wifi enabled and sounds like a really cool thing. I’ve thought about getting one off and on for a while now. We do not have central air conditioning, but would likely save some cash by manipulating our heating during the 12 hours we are at work each weekday as well as the 6 hours we sleep. Currently we are set at 72 degrees 24/7.
But, the company was recently acquired by Google. Great! But now I’m wondering if I buy it now will I be disappointed in 3 months when Google announces new features, etc?
I have a internet thermostat which I got before the nest came out, and is still available, cost about $100, does not do leaning, but allows me smartphone app access particularly to set it to an ‘away temp’ or to cancel it. I can also change the times and temp (4 time/temp set point per day that I can adjust).
So more limiting but does what I need. I can also pay a annual fee that would automate the home/away setting based on my location, this is new this year, and I do not like the upsell direction it is going in, but that function is there if one wants to pay.
It is also nice to be able to check the temp of the home (make sure the heating system is working), would be nicer if it could alert me if it is not.
All and all it is a decent much cheaper alternative to the nest, and it does save money, quite a bit actually.
If you are only using it to control heating and have a fairly well established schedule, I’m not sure what additional features you might need. However, is the firmware in a Nest upgradeable? Would you be able to upgrade an existing Nest to enable new features? Seems like that would be the case given that the background of the design team that make it.
The Nest is neat, but unless you have a reason to set your house temperature over the internet you’ll get 99% of the benefit of a Nest from a $25 off the shelf programmable thermostat. Whether or not you get a Nest you should get something to replace your current non-programmable one.
I’ve been mulling over HVAC control for my house, which has three (hydronic) heating zones and thus three thermostats, central AC with a single thermostat, and a number of control and comfort balancing issues. (The house is reasonably new but has never been upgraded from builder’s junk and poor choices made during construction layout.)
I have looked at the whole sweep of thermostats, from $20 round Honeywells to $1000+ wireless, learning, internet-ready ones. While some of my system problems need to be fixed by relocating thermostats or at least temp sensors, even as a tech/automation/gadget lover I can’t find any use for anything above a good 7-day programmable thermostat. All of the remote control and monitoring and “learning” stuff is realllll kewlllll, but I can’t imagine 1 person in a million actually needs those features for any reasonable purpose.
I’d suggest that good, easy to program and reprogram 7-day digital 'stats will do everything you could want heating/cooling control to do, barring that first week of cool-new-toy-ism.
I was looking at the nest and almost bought one until I saw that the latest version was having some issues with rapidly switching the air conditioner compressor on and off, and/or doing wacky things like switching on the heat along with the air conditioning.
I went with the $100 Homeywell as it’s easy to program with an iPhone / iPad app, and it can be controlled remotely in case we need to come home early, stay out late, etc.
I wasn’t impressed with the Nest thermostat but I’m really intrigued by their smoke alarm.
Remember, depending on the vintage of what you have now, you may need to run a 24VDC line to the thermostat. The Mothership dates from 1987, no juice for me 
We are currently planning to replace the old, builder-grade system in our townhouse, and the question of whether or not to get a Nest is on my mind.
Right now, I’m leaning towards no, for the reason that there have been some pretty serious problems reported with the Nest in systems where there is no dedicated C (common) wire for power supply, because of the way the Nest has been engineered to “steal” power from other wires when a C wire is not present. (This Amazon review by an HVAC professional goes into details.)
Ultimately, over and above the potential problems, I’m in agreement with some of the above posters: I don’t think the Nest will necessarily give me anything that an alternative programmable, wifi-enabled, internet-accessible thermostat would. The only real difference is the “learning” ability, and we’re comfortable enough with our existing programmable Honeywell thermostat that we don’t really need that feature.
(ETA: like ZipperJJ, their smoke alarm really intrigues me. If one has the thermostat and the smoke alarm, they interface so that the furnace will shut off automatically if CO is detected. That’s nifty.)