Dual Channel is fun, and night quality is getting better for smart phones. (good)
The Problem with using a Smart Phone as your DashCam is, humans are lazy. The one time we don't bother setting up the Smart Phone to record when we are in a rush, is when something is bound to happen. (and you regret nothing was recorded) If you have a spare Smart Phone dedicated maybe, but you're better off selling it on eBay and getting a true "Set it & Forget It" Mobile DVR Solution. I believe once people play around with the Smart Phone dashcam apps out there, they will eventually want to invest in the real deal. So it's a fun learning experience at the very least. IMHO
Another example, What happens when you're at the gas station or pulled over on the side of the road, and you pull out your phone from the window mount to send a text. Suddenly someone side swipes your car and drives away. (the potentially video captured event will be missed) It's really hard to not touch your phone for the while duration of your journey, unless you're an expert at voice commands.