I like the idea. A few thoughts:

- The "sign up for free" button takes me to an inescapable box which demands my phone number. Why can't I sign up using email?

- The cancel button on the sign up screen doesn't work.

- The Terms of Service and Privacy Policy links on the sign up screen don't go anywhere useful.

- I'd like to know more about the "optional extra services" and how much they cost before I sign up. I always suspect the worst when I'm pricing info is hidden behind a paywall.