I have been using the Brain Bag with a 4Z Vertical Brain Cell, Snake Charmer and Freudian Slip for about two weeks now. I didn't think a backpack could be this comfortable. I stuff it with a lot of things and it still remains comfortable no matter how heavy it gets. It serves my purposes very well. I also like how it stands up with the Brain Cell in it when I put it down. This was the bag I originally intended to buy a couple of years ago when I first heard of Tom Bihn, but I wound up buying a Super Ego instead because I do a lot of bicycle commuting. I thought the messenger style bag would be better for that, but I think the Brain Bag will work out very well in that regard.
The Snake Charmer swallows up a lot of cables and chargers that I carry around with me. It's really a nice piece of gear. The vertical Freudian Slip is a lot more useful than I imagined it would be. It holds a lot, very conveniently. I keep papers, pamphlets, pens, and even a large Moleskine soft covered journal in it. I'm very happy with the whole set up.
The pockets in the front of the bag hold a lot, as well. In one side I keep my Panasonic electric shaver and on the other side, a 27 oz. Kleen Kanteen bottle of water. In the top exterior pocket I keep some toiletry items like shaving cream, preshave oil and after shave balm from Art of Shaving. I don't travel lightly. I practically live out of this bag. It is exactly what I needed. Great purchase! No buyer's remorse here.