Functional and very comfy
With my gf using a multi-day gregory pack and me with this, I find that their bags tend to have many zippers and pockets. Maybe I'm tainted by how comfortable it is, but the sheer number of pockets doesn't detract from the overall functionality. A great pocket on the "front" to stuff a light rainproof jacket. An unzipped pouch along your back for water bladders or another layer of soft warm clothing, some mesh pockets on your hips and sides for water and/or snacks. The pocket on top has a water-proof seal on the zip with key clip, and an internal pocket for one extra layer of water-resistance for your phone or matches.
Side access to the main section is good, though I don't use it much.
What I would say is a down side is that the mesh all seems "wirey", really tough and not very stretchy, i worry that hard pokey bits might rip it easily (though haven't yet). The tops/openings of the two side pockets, also, aren't stretchy so you need a hole in your gear packing inside the pack to be able to fit a nalgene or similar wide-body bottle into the pocket.
The back padding/support can just be bent into a comfortable S shape to suit you with the help of your knee and the multitude of straps here and there (and around your waist) help keeps everything in check and the bag comfortably sitting on your hips even with a larger load.
A great bag, if this is how all gregory bags are made I'll be making more of them mine.