I don't get the use case either. Apparently it does ALL of the exact same things as your main phone, except... on a smaller screen? And using the same phone number...? But what can I do with it that I can't with the main one?
If I wanted a second phone, I could just get a small new one for $30 or so or just re-commission an older one I still have and charge (now only for alarm clock purposes, but it's working perfectly fine nonetheless...). And bollocks to the "less distractions" angle - it looks like it has all the exact same sources of distraction, and besides there's nothing preventing one to set up one's main phone to distract less. WTF?