99% of the time, I'm using the "tablet features" of my phone. I maybe get 3-5 calls a month.
A phone-watch would suffice for this.
If it could tell the time, provide me with notifications, has vibration and can tell if I move or not, this would be perfect.
The rest of the information I would consume with my tablet.
While all these micro-iterations on technology are great, and we have some amazing toys, I can't help but think that humanity is getting too DISCONNECTED from EARTH.
There's literally no way that today's battery density (or even in several years) is high enough to support more than a dozen calls, not to mention all the radios a cell phone requires (just think antenna length, not space).
I wouldn't expect a viable standalone phone-watch until 2025 barring significant advances in battery technology and cell antenna design.
It can't tell me whether I've walked or not, and I can't order a pizza with it, but I get all my notifications on it, which alone is very handy (pun not necessarily intended) for me.