From what I've gleaned from various sources online, the Hex Code is more stylish and compact. Both lack camera functionality but it's easier to take the phone out of the Book Book in the event that you do need the camera.
And from my own observations, the Book Book is made a little better, material and stitching wise.
Personally, I'd pick the Hex Code. I'm not in constant need of my camera and don't mind taking the phone out if I ever do need it. But more importantly, the Hex Code is about 30 dollars cheaper and I'd rather carry around a Moleskine than a Bible.
The Hex case flap folds behind the phone very easily with little added bulk. I use it that way when connecting to my XM radio dock (I do use a dock extender).I have the book book and I love it but it has a few flaws. One thing that made me switch back to my bumper is that the clear plastic covering the card leaves a smudge on my phones screen every time I closed the case and that was really annoying. Also, it's not easy to hold and type with if you hold it open like a book but you can flip the card side behind the phone and type like that but it's a bit bulky. It still fit in my pocket with some cash in there and like 5 cards. I like to alternate between my cases so I'll go back to using it again soon.
The Hex case flap folds behind the phone very easily with little added bulk. I use it that way when connecting to my XM radio dock (I do use a dock extender).
here's some pics of my BookBook. i've had it since around oct/nov.