I've only had luck with Apple Pay in Trader Joe's and Panera so far. Discover is doing 10% cash back for payments made in Apple Pay until the end of the year so I've been trying hard to find any stores that accepts it, but couldn't find that many places. If it were accepted by more retailers (e.g. CVS, Stars Market), I can see it being more widely used.
By the way, I remember Target, CVS, and some other retailers were working on their own payment system using QR code. I wonder what happened to it.