When I looked at the dimensions of the bungee wallet online I tried to get a physical representation of the actual size. I made a paper model based on the published dimensions. It seemed a little more bulky than I was expecting but I ordered it anyway. When it arrived I was pleased to find that the wallet was not as bulky as I had imagined. The edged are tapered off so that it fits nicely in my pocket.
I have no problem slipping the wallet in the front pocket of my jeans. My only concern is that it might slip out of my back pocket if the material (like board shorts) is slicker and you are sitting in a reclined chair or a bucket seat of a car.
As far as storage space, I don't carry cash. I can fit my drivers license, credit card, atm card, insurance card, dental insurance card, library card, Costco card, and two grocery store cards. That's a total of 9 cards and I have room for a few more or I could slip some cash in as well. Basically to use this wallet you need to prioritize the order of your contents. My credit card, ATM card and drivers license are on top since I use them the most. If I have to get my insurance card it is easiest to just remove all the contents from the wallet, thumb through the cards, pull out the one you need and place them all back.
If there was one thing I could change about the bungee wallet, I would make it water proof. I haven't done any experiments but I think it would be water resistant. But it would be sweet if it could be sealed tightly.