Sleeker designs in some of the new QS devices is see being promoted, especially those on sites like Kickstarter, lead one to be highly skeptical of their accuracy.
Some people think accuracy is not that big a deal, but it will become more important as QS devices look deeper into what is going on inside our bodies. You need good algos for that.
I posted a simple thought experiment with lots of pretty graphs on my blog that illustrates this.
Be skeptical of some of these new devices, and lets take accuracy seriously.