I got this bag because I needed something that is portable (fitting into smallest overhead bins), well padded yet smart looking and doesn't scream "photo gear" when traveling.
My main bag is a medium Lowepro shoulder bag that fits all of my equipment: Canon 6D with grip, 24-105L, 80 mm, 50 mm, Tokina 17-35, Canon Speedlite, two TTL wireless transceivers, several filters with cases, cleaning equipment and such. So I figured it would be overly optimistic to try and cram it all into this backpack.
The good news is, EVERYTHING does fit in, albeit with some juggling. The camera with grip and 25-105L will occupy the entire removable insert, but fits nicely (laying on it's back, lens pointing up). Two other lenses fit in the bottom compartment, including the large Tokina; the rest goes in the upper, together with an iPad, a thin nylon shell jacket and an apple, the edible kind (just like in the promotional video) :). I did have to modify the bag slightly by adding some velcro glued to the inside walls, then using the padded dividers I have left over from other bags. But that was not a must, just a minor convenience. Don't expect everything to be instantly accessible if you see a photo op while walking down the busy street, but it works fine if you have 30 seconds to sit and unpack what you need.
I guess it's needless to say that if you're planning to attach a tripod on the outside, it will have to be a very small and light one (say up to 16")
Main gripe and reason for 4 stars: the oversized zippers, that are supposed to make opening and closing easier, actually get in the way. Especially the upper one tends to twist at the ends when fully open, so closing it can be very tricky.
EDIT, a month+ later of constant use: This is now my main bag... That says a lot. And for what it's worth, it gets complimented on all the time, clients tend to notice it (which wasn't the case with regular camera bags), let's call it a nice marketing tool. The zippers softened somewhat and everything is holding up nicely.