Mike wrote a review of Arc'teryx Cierzo 35 Backpack - 2136cu in on September 20, 2011
It's always hard to find a light summit/day pack in this size without a frame. Good for a follower or a leader/long day in the hills. Fabric is more durable than similar packs with the flimsy siltarp material.
Pros: light, holds a lot, durable for the weight, no frame (removable bivy pad), compresses enough to stuff in a larger pack, rope strap on top, Micro daisy for clippin' rockshoes, helmets, etc. Removable ice tool holders.
No hydration port (easily fixed with a knife). But really!? Such a drastic oversight makes me wonder what other oversights I'll discover later on.
Shoulder straps designed for barrel chested tumblers. I'm 5'8" and need to pull the shoulder straps completely tight. So basically, they made the fabric/padded portion of the shoulder strap insanely long.
Next model? Add a floating lid, hydration port, stretchy side pockets (cilogear has this dialed), and a longer/thinner strorm collar so you can get more torso into the bad during a shiver bivy. Also a re-enforced loop on the other side of the rope strap so you can double back the strap over the rope, making it more secure.