Haven't gotten a chance to take this out on the trail (or mountain) yet, but I have fully loaded it to try out the harness and waistbelt. While I was at it, I gave it a dunk in my tub, and everything inside came out dry.
The suspension on this thing is great. Really transfers weight to the hips well, and the hippod things (which look like they may suck) are the best hip padding I've had on a pack. The outside has a bunch of loops and lash points, which is always a plus. I've never had an Arc'Teryx pack before, but if they're all built to this quality, with this level of detail, then I'm sold on them.
My previous pack was a North Face Primero 60, which is definitely a nice pack. After 20 miles a day in the Eastern Cascade foothills, though, I was definitely feeling the pain on my hips. This pack has less volume, which I can definitely deal with, and a lot less weight. Being in the Pacific Northwest, the waterproofing is a killer feature, and this is going to be my go-to backcountry pack year round.