At significantly less than 4#, and over 4000ci, this pack is for those who leave the kitchen sink at home. I carried mine around the tetons for 3 days. I got used to the top-loader after switching from a top and panel loading e-frame. My only complaint was the hip pads: they don't come very far forward, so my 35" waist had a few bruises. My solution next time will be to use the cut-off sleeves from a fleece jacket to slide over the straps.

I purchased this pack after getting sized at a local outdoor store. Pack fits perfectly! Very light and has tons of room.

I used this pack for a 6 night trek through the Yellowstone Backcountry. The lightweight attracted me, and did not disappoint. There are a few nusiances howerver that should be considered.
A. this is top loading only, meaning you will unpack it completely each night and repack it comletely each morning. As soon as my group could consume enough food ( I carried supplies for 4). I was happy to get my sleeping bag stuffed into the external compartment. This way I could set-up camp without unpacking the whole bag. To do this, you need a very compact sleeping bag. My Eureka 30 degree bag was about as heavy a bag as can be used this way. There is no way a low temp bag is going to fit (I tested this theory with my -30 Northface down bag.
B. I echo other comments about the elastic side pockets. Your Nalgenes will be out of reach in these pockets.
C. The belt pockets are well sized and convenient....but your topo map wont fit here....so it gets stuffed out of reach in the overhead or into your pants pocket.
D. The lower hang loops are a big concern. I carried a 7lb 3 man tent on these and it was a struggle to attach and carry here. The bag would be signiticantly improved if there were web straps or a more convenient maens to use them. As is, the pack is not well suited for carrying a tent........better for just an external thermarest in a stuff-sack.

Bottom line is I pushed this pack to its limit of near 35 lbs gear revealing some of its shortcomings. You might consider another bag if you will carry a heavy tent regularly.

I got this on sale at REI, attracted by the low weight. My other pack is the 5,800 c.in. Dana Terraplane which is ~7 lbs, so I figured I will try to shave off 4+ lbs of the pack weight and try to bring less crap on my trips.The fabric of the pack got ripped by the airline luggage people on my very first flight, while the Terraplane has survived 20+ flights w/o any trouble.The size is enough for only 2-3 day trips. Won't work for winter and for week+ trips.I am back to my Terraplane.Bottom line - expect no miracles. Lighter pack -> more fragile -> less space.