Awesome bag. I commute to work on a battery-assisted bicycle (on sunny days), and need to carry my 13" laptop + assorted cables & office things. Works perfectly. The only improvement I can think of would be to add a carry handle.
The strap system needs improvement. The sliding buckle sits right on my collar bone, regardless of which way I attach the strap. It seems like the strap could be simplified overall; does it really need to be reversible?
The tweed material feels like a wool sweater against my back, but otherwise a very nice bag. Feels like great, durable construction.
The bag fits against your back really well, and the two drop pockets under the flap are great.
This bag is very well-designed and comfortable. One of my favorite features is the strap that you can fasten around your torso to keep it from swinging off to the side (which seems to happen when I stop at a light with my other bags). I also love the system where you can velcro in the "accessories"--I don't always bring my laptop when using this bag, so I can use that space effectively by taking out the laptop sleeve, but when I do need my laptop, I know it's secure. The spaciousness and the accessory system make this bag truly "all-purpose."