I'm still trying to figure out what exact user case having a digital watch solves. I mean .. I have a phone which shows time, plays music and can tell me who called / sent me a signal message. I have issues with having to charge my phone so having another device that I will have to charge will not make my life any better.
You say "digital" rather than "smart". Digital or analog, a basic watch has that single advantage of being mounted on the wrist. It is always there, supporting a quick glance when you don't have time, free hands, or social context to pull a phone out. Once you add vibration, now you open a class of discreet alerts. Even an offline watch can give you a silent alarm function, which is great to reduce disturbance to you…
I meant smart. I don't have an analog watch fetish. :)