I've been using this pack for all my mountain adventures for two or three years now, from day hikes to two-day mountaineering enterprises as well as rock and ice climbing. It's a great lightweight pack and the pockets are so handy, especially the waist ones. I really like the fit, how it distributes the weight onto my hips. When wearing it with a climbing harness, the waist straps can get in the way a bit.
Over time, I think I have really pushed this pack to its limits. I've had to be careful when packing it full as, due to its lightweightness, if you don't pack it well, it can be uncomfortable. And now, after some extreme ventures the back support has pretty much caved in. This is not a fault of the rucksack at all, but just a word of warning to those who become as attached to it as I have, that it does have its limits!