I have skied with this a few times (resort without canister, resort with canister, 'sidecountry') and have deployed the airbag for travel but have *not* used this in a real-life slide. Despite that, I don't see a reason not to give it 5* based on my experience so far.
First, the bag is well designed, with a streamlined shape that fits nicely on your shoulders and somewhat tapers towards the hips, making it a nice snug fit around the waist. If you adjust everything properly, it should fit as an extension of your body, with shifting or sliding form side to side. The shoulder straps are comfortable, the hip belt fits well and is easy to operate with gloves on (tip: adjust the female buckle [right hip] before u head out, then you only have to adjust the male buckle [left hip] with gloves on. One hip belt has a small pocket, which is nice. The belt that goes around your leg and up thru your crotch is also easy to adjust, and fits well over snow pants.
One smart feature is that the bag has built in 'storage' for the extra straps you are not using. For example, the leg straps and ski carry straps can be store into internally built and designated pockets when you are not using them, which is great for not getting snagged on lifts and such.
I know there have been complains about using the ski carry, in that if your zippers meet at the top center of the bag, the bag will peel open with the weight of the skis. As other reviewers have highlighted, this problem is avoidable by having the zippers meet in the bottom rather than the top.
As far as storage, the airbag it on the top and inside, closest to your traps, with the rest of the system below that. The airbag takes up some space, and this would be expected. In the same pocket as the airbag, you would put the canister, which is very easy to attach and has its own designated pocket. Beyond that, there is ample space for: extra layer, extra goggles or lens, nalgene, thermos, and the odds and ends (wallet, sunscreen etc). The front pocket then holds the avy gear, with their own designated pockets.
The only complaint I have (u can't have it all, right?!?!) is that there is no hook to hang a camelback. I suppose this is because that could potentially interfere with the airbag system, BUT the shoulder straps have zippers and holders for a hydration hose. So maybe I need to do a little more digging here....
As far as the airbag goes, it has its own designated pocket. I've deployed the airbag for practice and travel (to empty the canister). It is easy to repack (there are instructions right on the airbag itself).
The bag seems to be high quality and durable. I am very satisfied with what I've used it for so far, but again, I have not deployed it in the field. I hope this review helps iron out some of the details of the construction and features of the bag, if anything...