My review of the Deuter Race X air 1:
Overall features
1 main compartment with elastic top sleeve for bladder inside, one front compartment that has some smaller pockets in it, two mesh elastic side pockets, and a zip away helmet holder (great).
Unpadded 3/4 inch wide webbing waist belt, sternum strap that can slide on its attachment points up and down so you can place it where you want it.
100 oz bladder that has complete wide open top, folding top seal, angle bite valve that twists to lock closed, and comes with a cap to keep it clean.
Suspension system keeps pack off your back as advertised, rigid frame extends to belt attachment points and provides little nubs that rest on your hips and take some weight off your shoulders.
Highlights:
I think the helmet holder is my favorite feature of this pack. It is like having a small pack with a magically large capacity. The helmet holder material is a 360 degree stretch fabric, and held my fairly bulky northface shell easily.
The suspension system is nice and comfortable. The weight rides low and on the hips.
The shoulder straps are unpadded webbing material, but feel just as comfortable as padded straps I am used to.
Overall, material and construction seem high quality.
Gripes:
I think a pack of this quality should have a better belt. It doesn't have to be padded, but 1.5" wide webbing (as my camelback has) would be more supportive and comfortable than the 3/4" provided. With that said, it still does the job. A better belt would also facilitate adding a front access pocket on the belt, which would be nice for access to some things without taking off the pack (like an MP3 player for example).
I like the bladder and the bite valve with cover, but wish the tubing was detachable, as on my polar pack bladder. It really makes it more convenient to pull out the bladder to fill or clean. It would also be nice if the tube was insulated. The tube could also be longer, as I have been using an under the armpit tube routing with my camelback, but the tube is too short to use this routing with my Deuter.
I bought the pack mainly for the suspension, to relieve shoulder stress and reduce back sweat. It does the job in these areas, much better than a simple foam backed pack. But, a better belt as I mentioned, would make it better and easier to transfer weight to the hips.
I like big packs and felt at first this one might be a little too small. The frame curves back away from your body toward the bag, so when you load it, the bag also seems curved rather than wide open, but I could still get plenty of stuff into it, and the helmet holder has alleviated any fear that I won't have enough capacity for jackets or other foul weather gear.
Overall, it almost looks too simple compared to some of the packs that try to add every feature, zipper, snap, webbing , bungee cord, pocket, etc under the sun, but it has what you need and is very functional, comfortable, and well designed.