Used it on the bus/train and at eat today. Can't use my watch yet as I'm on beta 3 but using the phone vs contactless card, the phone seems quicker, I think its due to the range being better on the phone.
On the bus/train I just double clicked the home button, left my thumb on the touch ID, the screen shows "Ready to pay" and when I got to the barrier I just tapped the top close to the reader, little vibrate and green light (On the reader) and the barrier opened. No delay vs contactless.
FYI you don't have to keep your thumb on once "Ready to pay" shows.
That's good workflow, many people complain about Apple Pay will slow you down and the line of people on Tube and busses. You sound like it takes same amount of time - you just need to prepare.