The Interface is slick and simple, the devices and services are reasonably priced, and there's a lot of peace-of-mind that such an offering can provider.
However, as Extremetech points out, "Just imagine what Google could do with a real-time, high-res video feed of your home. Where the Nest thermostat might give Google some behavioral data — how warm/cold you like the house, your comings and goings — it pales in comparison to Dropcam. With Dropcam, Google would know exactly what you’re up to at any given time. If you’re preparing dinner, Google Now might automatically prompt you with “tips on how to make the perfect souffle.” If you’ve just brought a newborn baby back from the hospital, you might suddenly find lots of Google ads for diapers and strollers. If it hears you shouting at your game console, it might tailor your search results to show some different, less-antagonizing games."
Then again, this line of work has gone a long way to making me paranoid. So perhaps I'm overreacting. That Nest smoke detector does sound nice...