Apple's Passbook has had a rocky road. When it was first introduced in iOS 6, it seemed like an excellent idea. You could store all of your loyalty cards, tickets, and other mobile payment items all in one place. But in practice, Passbook hasn't been all that helpful. Not many retailers' loyalty programs are included in the app, and getting information in there is harder than it has to be most of the time.
But Apple isn't giving up, and neither are retailers. GigaOm has a few good examples of how certain retailers are using the app. Gift cards are now a big deal within the app, and CashStar (which sells digital gift cards for big brands) says one third of its cards are opened on a smartphone, usually an iPhone. The app is also easier to use, as more companies build an actual workflow into it. And customers are not only learning how Passbook can help them, but they're growing accustomed to the idea of digital gift cards and currency.
Passbook is still around in the upcoming iOS 7, though it's only gotten a new icon and a barcode scanner (which itself might help with ease of use). The dream of keeping all of those loyalty cards, gift cards, and ticket stubs on your phone instead of in that drawer at home is still alive, and hopefully someday Apple will make it happen with Passbook.