Regarding the technology - unfortunately, there is no much technical details released by Apple so far, so a serious thorough assessment is impossible right now. However, it looks like Apple Pay uses some form of tokenization, which means that breaches like Target or Home Depot will be impossible as merchants will not be exposed to the sensitive cardholder data. A token, which is generated by the device when you add new payment card to the Passbook, will be stored in the secure element and used instead of actual magnetic track of the card. So far so good.
As far as possible effect on the payment industry - it's still unclear whether this system is open or closed. As many Apple things it can be proprietary, so if others can only imitate it rather than follow, its mainstream acceptance can be limited. NFC is open standard, but NFC is just a communication part of it. There are recent precedents, however, when Apple created a relatively open standard in retail - iBeacon.
And finally, like many things made by Apple - it's simple, elegant, and convenient.
Anyway, I am going to try it as soon as I get my iPhone 6.