I used to be a fan of very basic climbing-oriented packs for skiing, but this has changed my mind. The ski attachment and "safety box" together make for super-fast transition in ski mountaineering terrain. And I love the water battle holder, especially for quick refills from natural water sources. I've started out on 12-hour tours with only a single bike-size bottle of water, and then just easily refilled along the way. Dual access to the main compartment (via zippered back and traditional top loader drawstrings) is very convenient. The ice axe holder also works well for securely holding a ski pole (by quickly sliding apart the two ski pole sections, then reattaching) when taking out your ice axe.
Some nitpicks that prevent a five-star rating:
-- A few relatively minor durability issues, all easily repairable, but don't feel they should happen.
-- Probe sleeve needs to be a wee bit longer. (Shovel pocket though is fine though for the latest "neck-less" designs.) So when I'm bringing a really long beefy probe, I put in the hydration sleeve, quickly accessed through the zippered back.
-- The "Summit Comfort" pad in the safety box is best to swap out for a basic cut-to-fit blue pad (lighter, more insulated, and fine for internal pack protection).