I've used it on overnighters and on weeklong winter trips. Loaded it with at least 60 lbs and it carried well.
The waist belt is very comfortable and moves with me very well, the shoulder straps are well padded too, although the waist will support most of the weight easily. The load adjusters are well placed for use while wearing and work great.
The sleeping bag compartment fits even my 0� winter bag ( Marmot couloir) in a large sea to summit dry compression sack.
I like the front access to the main compartment, the buckles work well and didn't ice up in sticky snow.
Cons: seems small for a 65L, noticeably smaller than the Arcteryx and Osprey I've used. The vertical zipper on the rear facing pocket is pretty much impossible to get anything in or out of when the pack is full, I try not to use it for anything not soft and stuffable. It would work for a small jacket, a beanie, some socks or a long sleeve shirt. I wish it was more functional, like the pocket on the Arcteryx Bora 65.
The compression straps are well placed and were strong enough to hold my skis on with my Scarpa Mobe boots attached.
I actually like the design of the Arcteryx bag better, but the comfort of the harness makes me happier wearing the Gregory. I'm 5'11" with a 32" waist and I got the medium.
All in all, a great pack.