I'm a big fan of this pack. I felt like Osprey put a good design together and every feature has been thought through. The comfort level doesn't really change as your pour the weight on, It carrys like a dream wtih 30-40 lb. The volume limits how much you can carry more than the comfort does. I used it on a handful of weekends in Utah and a two week Argentinian Patagonia trip where it took everything I could throw at it.
I really like the waistbelt more than any other pack I've had or tried on. As a somewhat thin dude with boney hips I have a hard time finding packs that don't leave my hips hurting the next day. For the hip pads they use a thinner and more flexible foam than most other packs. It's designed to hug the hips instead.using a lazy design an just putting a buch of soft foam. The waistbelt also has small zippered pockest that I didn't really find that useful, they're bit enough to fit your keys (maybe a small digital camera would fit, but I was lugging around the SLR).
The back was comfy, it's a corragated closed cell pad. It comformed to my back shape well and rotated torsionally better than most (especially considering the size and load). The back breathed fine for me, but I'm not an overly sweaty guy so I can't really say how much better the Atmos is in that reguard. I didn't really notice the shoulder straps, which I guess means they were pretty comfy and it fit well enough to take most of the load just on the hips. One thing of note, all the foam in the pack is closed cell with mesh convering. The major advanatage of this is that it doesn't absorb your sweat, so you don't get that cold shock of disgustingness when you put your pack back on after a break. I liked this alot.
I thought the trekking pole stow and go system would be more of a gimmick than anything, but was pleasantly suprised to find it quite useful. They included a pack cover, which was nice of them but it immediately went on my gear shelf. Maybe I'll take it if I'm going out knowing I'm walking into a monsoon, but that's about the only use it'll get. It took up too much space for a pack of that volume. Not having to dig inside the pack for the water bladder was nice too, it's behind the back panel but not inside the pack. The the pack was fully loaded and stuffed, the pockets on the side didn't take 32 oz nalgenes too well, but were perfect for drying sweaty socks, trail mix, or the 20 oz target brand nalgene knockoff bottles. The stretchy pocket on the back is adequate for small stuff like a guidebook or some food, maybe a light rain shell. It's covienent, but didn't eat anywhere near the amout of stuff that the Atmos does.
All in all, the cons were very insignificant for me (and probably things good for other people) and the pros were way better than any other pack I could find. Before price is considered, this is a great pack. Realizing that it's cheaper than most high end packs makes it a steal. I should also note that I've used Osprey stuff before and it lasts. I'm still using my 7 year old Vertigo for climbing. The thing has been abused on a weekendly basis and is still going strong and has seen tons of abrasive rock. I look forward to this same quality with the Kestrel as well.
