The space of M2M and the internet of things is a new battle space. The protocols to control your home appliances are being set in the coming years. Zigbee is the “most unliked” defacto standard for that so far.
But Zigbee messed itself up completely with SEP2.0: a totally overdesigned protocol. Google and Nest have just launched Thread. It uses the same hardware and radio protocols as Zigbee but a different software layer on the top. This Energati article does a reasonable job in explaining some of the technical issues.
There are plenty of protocols, both IP based and non IP based. The article below from Engerati also discusses new variants of bluetooth. JenNetIP is also a quasi standardized option promoted by NXP. Zwave is the most popular (somewhat proprietary) protocol so far in practice; it has better in home coverage in part thanks to the lower frequency band that it uses. In the author’s opinion in the stage of early market development in home coverage is king; and Zwave is proving it in the market by being the most popular protocol. Wifi should be the other contender, for the simple reason that in an increasing number of homes it provides good coverage to the smartphones, tablets and other wifi gear. It is not exactly specialised for low power small software applications but hey, proper implemenmtation will go a long way. Your smartphone can also run Wifi.
Will Google and Nest make it into serious market deployment: maybe. Don’t get fooled by all the partners they claim to have: good old fashioned hype and low/no real commitment. Technically speaking they are totally right about SEP2.0. But the main Zigbee issue was not fixed: coverage.