I just did a short hike in the Grand Canyon (rim to Indian Gardens) and I would have liked to have had this pack with me. For that hike I used a Camelback Blowfish with a 100oz bladder. However, the MountainSmith would have worked better for me. It has space for plenty of water and if you have a CamelBack Stowaway bladder (70 or 100 oz), that will attach easily to the Mountainsmith.

The nice thing about this pack is that the camera slips easily into the weather/rain resistant top compartment and there is room for 2 other lenses in a compartment that is easily accessed on the back of the pack. When hiking I only carry two lenses plus the body - if you are looking for carrying much more gear than that you will need something else.

As to adequacy of volume for a day hike, it has room for a shell, food and other gear. It may be a tight fit, but no more than you'd expect. Access to the main compartment is through the back of the pack.

The pack has outside mesh pockets and compression straps and plenty of attachment points. The pack is built with contours that sit on your hips and the hip belt, though not fancy, is made of 2" wide webbing and has a substantial Rock Lobster buckle. The tripod/gear straps on the bottom are handy and well made.

There is also a wide rubber coated webbed handle at the top of the pack for grab and go carrying.

Materials are high quality and construction/stiching is very good.

There is a lot to like about this jacket, but for me there were a few things that were deal killers. I think Oakley tried way too hard on this jacket.

Cons:

1) Instead of velcro, this jacket uses a lot of rare earth magnets. And they are tough to work with. The front zipper storm flap is held by magnets and they don't like to let go. The pocket flaps are held by magnets and that makes me a bit nervous since I'll carry a camera and other gear in those pockets that may be sensitive to a magnetic field. Also, when you walk up to your car to put the key in the door the magnets in the pockets stick to the car door. Imagine if you are putting your skis or bike on the roof rack...Pretty infuriating.

2) the wrist gaiter is cumbersome.

3) the sleeves are very long. Not so bad in the body for layering and such, but the sleeves come down to the very tips of my fingers and when tightened around the wrist there is a lot of bunched fabric.

4) the zipper gauge isn't compatible with any of my inners that do zip into my other shells without any problem. (Patagonia, Red Level, Nike).

5) The zippers are spring loaded - I had to fumble with them.

Pros:

1) high quality fabrics all around.
2) YKK zippers are of good quality...just an odd size.
3) Warm enough as-is for most winter activities without using a zip in fleece. As long as you are moving, you'd be warm.
4) Fabric isn't noisy
5) For the back country uses, it has built in Recco avalanche reflectors.