Pretty Cool indeed, not epic though.
I don't have that much time with this pack yet, but I'll described my thoughts so far...
Like the capacity, a lot but not huge. Glad I got this size instead of something in the 20-30L range I was originally thinking. It's actually fairly compact until you start expanding the filling the top of the main compartment in the collar. There is a small velcroed pocket inside the main compartment on the backside as well as on the underside of the floating-lid (complete with key leash).
Great details - waistbelt gear rings as well as their fancy biner loops - still learning to take advantage of those. Like the stowable hipbelt, I used this a lot this weekend while wearing my harness. Seems rugged where it needs to be and the materials thought out. LOVE the dual front+rear handles, great for throwing it around.
Wishlist - the removable pad is a cool idea, but unless I'm doing it wrong, it's really hard to get out. Not to mention getting it back in if you don't do it before refilling your bag. Small wish for some external small pocket and/or water bottle storage (I guess I can add a bottle pouch).
Beyond the stuff above, it has enough attachment points outside to temporarily biner stuff on while you move around the rock. The function of the main compartment is as you would expect from any top-loading floating-lid pack.