It's a solid bag. I've had one for a few months and it shows barely any sign of wear at all. It's not a backpack, but I like to travel light and it always seems to carry enough.
It does tend to fall into this swinging rhythm when I walk, where my laptop ends up smacking against my hip. No damage or anything -- it's just sort of annoying. The strap also supports the weight of the entire bag, and it feels heavy on my shoulder after a while. It's not the best thing for walking around the city a lot, but it's perfect for commuting.
I wish they made this in backpack form.