Here's a video (below) demonstrating it in action. The phone goes on the right, money goes in the middle sleeve and there are two credit card slots and an ID slot on the left. You can answer the phone without taking it out by flipping the case backwards — which is slightly awkward, but not too bad—and slide it up and out for a photo. The cash slot holds a decent amount of cash, and the credit card slots can theoretically hold two cards per slot, but it would get pretty crammed.
This thing is great. Rather than keeping a wallet and a phone in my pants, now I can carry one thing that is about the same size as my wallet. The only problem is that I'm the kind of guy that likes to keep all his cards on him at once, so that, for example, I'll be prepared if I need to go to Blockbuster, or get my car towed, or show my dentist or doctor my insurance. But is that necessary? Can't I just leave those sometime-use cards in a stack at home and insert it into the BookBook when I need it? Do I always have to carry my business cards around in my wallet in case I run into somebody? Would an email address do? Yes, most likely. So this case has changed my use habits a bit as well.
Not only does this $US60 case protect my phone and carry my essential cards and money, it cuts down my pocket bulge dramatically. Oh, and it looks like a small distressed leather book, which is classier than the plastic-build quality of other iPhone case wallets.