I was deciding between the Timbuk2 courier bags and the Osprey FlapJack and finally chose to go with the Osprey.  The bag is really well made and thought out, the strap is comfortable and the fabric is relatively pliable and not stiff like thick cordura.  The pliable fabric allows the bag to conform around your body making it very stable and comfortable.  The bag is not super huge but big enough to carry a laptop, gym clothes and a pair of shoes.  One of the main reasons I got this bag is because of the handle on top which is only available on a few Timbuk2 products.  It is both stylish and functional, perfect for work and commuting on my bike.  I chose the more fashionable Khaki color because I already have several black and blue 'utility' bags .  My only criticism is the strap is a little short for my long torso, it's not really a problem it's just a little difficult to take off if wearing a heavier jacket.