The problem is that it needs to be told what it's supposed to track and it homes for where it launched. Following someone walking is very different from following someone when they're moving quickly. None of their video showed the latter, which tells me that they couldn't show it (after all, it'd be impressive).
Don't get me wrong, it looks like it'd be handy for a lot of purposes and they're moving in the right direction, but the pet analogy is really what I want to see for action shots. If I am bothering to charge and carry it, it needs to be able to do them with little-to-no planning or configuration. We're talking push of a single button simple. In a way, the best solution would probably be the simplest one: Have the smartphone stream GPS coordinates to the drone while tracking... It'd beat object recognition and keep it close the whole time.
As I think about it more, I can see some great uses for it. It's very cost effective for the capabilities and the size would make it very practical to carry around. I do think the size is great and the way it folds up really small is the best part of it. If I was a travel blogger that wanted to add video of my adventures, this would be an obvious choice.