Lauraleewrote a review of Osprey Packs Sirrus 24 Backpack - 1400-1600cu in - Women's on December 21, 2011
I've used a small camelback pack that allowed me to carry the essentials and a liter of water for the past few years. After purchasing an Osprey, lets just say I'll likely never purchase a camelback again.
I purchased this pack to do a couple of long dayhikes where it was necessary to carry more water and snacks on the trail.
The pack fits nicely. I actually have a shorter torso for my height, but the larger size fits better for this pack. It's comfortable, and I love the ergonomic hip belt (nice to be able to adjust as I add/remove layers)
I love how I can carry everything I need for long dayhikes, or I can use the straps to compress the pack size making it less bulky. I also attach plenty of things to the straps that I either want quick access to (like my microspikes, hat, etc.) or at times I need my snowshoes but not the entire trip I can strap them and leave them hanging on the side.
There are plenty of pockets, and on my short day hikes, I don't even use all of them. On longer ones they are great for stashing granola bars, crackers, etc. I often use one of the side mesh pockets to carry an apple, orange or another piece of fruit as it seems to survive longer there. The Nalgene bottles fit in the pockets, although it is hard to place the bottle back in with the pack still on your back.
The one thing I don't like about the pack is the trekking pole attachement. Perhaps my poles don't fold up small enough, but I'm not a fan of having the poles right underneath my armpits. If I'm not using them I'm fine with either strapping them to the back of my pack, or carrying them in my hands.