The hip-belt lumbar support is poorly designed: under a heavy load it literally gave me a blister/pressure sore on my sacrum. To relieve the pressure I rolled up some socks and taped them with duct tape to either side of the lumbar support.
I also had to put more weight on the shoulder straps then I usually do and got blisters on my collar bones!

The pack does OK when carrying a modest weight: but the whole idea of this pack is that it's supposed to let you carry a lot of stuff.

A minor point: the ice axe loop elastics pulled out of their retainers with the first use.

Overall this is unfortunate because I otherwise like the pack design for mountaineering.

I used this back for a 20 day trip in the Wind River Range in Wyoming. It worked well. The pack fit comfortably (even though I wish I got a large, my torso size is right on the edge.) The hipbelt, even with out doing the fancy molding process was comfortable. It was very easy to pack, being basically a barrel. It's actually fairly water resistant. After being in a puddle for a half hour in Kentucky on another trip the inside was still dry. No rips or holes even after dragging the beast up rocks. It held 80+ lbs. with relative ease. It also has just enough extra features that I used them all, but didn't want more.

On the downside I had a few things brake. One of the buckles attaching the top of the pack to the back of the pack partially broke. One drawstring broke, all though that was partially my yanking on it. Also, one of the ice axe loops broke, though again, that was partially my.

Really, my only design complaint was the Ice Loops that we actually metal bars the held the bottom of your ice axe, and a elastic top to secure the handle. The elastic kept slipping making your axe bump around and I would have to fix it every other brake. However, there is a standard ice axe loop that you may use.

Overall I really loved this pack. My friends Gregory and Osprey packs failed where mine held up. (Only the NOLS Deuter pack really could compare.)