One unstated, but probably critically important, point in the article is the teams' work ethic. There was a thread on HN and I believe it was one of the YC partners or founders saying that these guys barely slept. They really demanded a lot out of themselves and were all accountable. To go from concept to a large round of funding in such short time probably speaks more to their relentless work ethic than anything. And it probably wasn't just hard work, but also working smart. Hope I can one day be on a team like that.
I'll also add that I absolutely love the product, it has so much potential for future applications. And the market for it is essentially everyone IMO.
This is one of those projects that probably made it really easy to keep working and get up in the morning to work on. Amazing product and very clean/stylish. Definitely one of the most exciting YC companies. The evolution pictures on their site really look great. Clearly one of the most exciting wearable projects out there.