I think all went pretty well today using Apple Pay on my Watch. I used it in:
Caffe Nero
Costa
Tesco
Le Pain Quotidien
The only places I didn't use it were Waterstones (because they said they wouldn't have contactless until tomorrow) and on TfL (because I stuck with Oyster as I have a railcard discount).
The only thing I don't like is that I don't get a list of recent transactions.
Open passbook , click on the required card, the press the i button down in the bottom right corner, this will bring up the card information including transactions