Setup - Simple
Comments: Was forced to add a card because the current card within my Apple iTunes account isn't supported by Apple Pay.
Brick & Mortar Use - Simple
Comments: Phone lights up when in close proximity highlighting the card choice. Once ready, placing your finger on the fingerprint sensor leads to a completed transaction in less than 2 seconds. User is alerted of the successful transaction with a push notification. With that said, no simpler than swiping a credit card and whilst Apple launched with some of the US' largest retailers, many are missing.
App Use - Simple
Comments: User places finger on fingerprint sensor which auto populates the shipping address, billing information and proceeds to checkout. User is alerted of successful transaction with a push notification. The benefits of app usage are much higher than brick & mortar. Setting up new user profiles and/or credit cards via mobile shopping is the major reason why so many users never checkout. It is painful. Apple makes the process simple and will inevitably improve the conversion rates for the apps utilizing Apple Pay.
Browser Use - Not yet available
Comments: One could argue that Apple is holding off on a launch for mobile browsers to incent developers for iOS only development but one should expect a version for mobile Safari at minimum.
Bottom line: This launch has been the most ambitious to date, yet Apple pulled it off. Simple, seamless and an extensive launch list for both Brick & Mortar and Apps. The benefits within Apps greatly outweigh Brick & Mortar but Apple seems to be the catalyst to get the mobile payment game started.