I'm one of those people who can get a bit obsessive about carryology. When I set out to find a new backpack, I had several criteria: it needed to be waterproof, it needed to have an easy-access laptop compartment, and I needed to be able to stuff more than the allotted volume into it. Because I am occasionally rummaging through my bag in meetings, I also wanted it to have no velcro so that it wouldn't be noisy. I also wanted the hip strap to be really solid so that I could actually put the weight on my hips, as you are supposed to when carrying heavy loads.
the Edge 40 really knocked all of these goals out of the park. As everyone knows, it is waterproof. I love the rolltop; it's fun to use, and quick to open and close, and you can really stuff it to the brim and get things home (although that will of course compromise the waterproofness, but every bike ride isn't a deluge condition). The shoulder pads are really wonderful. Very few daypacks are designed with adjustable straps at the top of the shoulder pads, but this makes a huge difference if you are carrying something heavy downhill, and loosening them allows you to counter balance the weight. The hip straps are really substantial, and this is by far the best backpack I have ever worn on a bike. I also really appreciate the rain fly, although I have yet to use it in a heavy rain condition. The zippers are all high quality and don't catch. Using waterproof zippers might have been a nice touch, but unnecessary because if it's really raining hard I'll just pull the rain fly down.
There is a bit of room for improvement, but I'm talking really minor details that would make it the 100% ideal pack in my mind: it would be nice if it had included bilateral waterbottle pockets to store water bottles and also bike lights or gloves or other loose things i like to stuff in them. (accomplished this with the MOLLE accessory pocket, but would have been happy if it was included). Also, the external pockets can be hard to rummage through when fully packed; it would be nice if the zippers were a bit wider. A nice touch would be some 3M reflective material on some of the straps for night visibility. The external laptop compartment is a bit tight, and hard to slide a laptop in if the other pockets are stuffed. this could be remedied by reinforcing it, although the rolltop was so easy and fast that I've just gotten in the habit of putting my laptop in the main compartment of the pack.
Other than those really specific details, this is literally the best commuter pack on the market that i have found, hands down. It is cheaper than many of the other leading bike bag brands, and much better constructed. Of the boutique bike bag shops, I also find this one to be competitively priced, well-constructed, and perfectly suited to my needs in a backpack. I wouldn't hesitate to recommend this bag to anyone asking me about backpacks.