Great build. Made of fairly sturdy material. It's about 16" x 7". It works really well for urban trekking and small shopping and carrying small essential with bus maps, GPS, and the like.
The one thing I'm not crazy about is the strap design. It would be better if the adjustment buckle was connected to the top of the bag instead because it makes it awkward to grab sometimes. Also the strap can be lengthened almost too much so when its fully shortened it's still a little too long, which isn't so great for a more slender guy like me. Having a little more slack to shorten - when it's a little more extended already - would be nice rather than having too long of a strap when fully shortened.
The strap position feature on the bottom of the bag is nice for switching shoulders, especially if it's just hanging over one.