I would love to give this five stars because I tried on 10+ packs in this category (including the heavier Deuter Aircontact 55+10) and this one came out on top. But I am a little worried about durability, especially with the thin skeletonized buckles. The hip buckle didn't release cleanly the first time I wore this and almost snapped it off as I was trying to get 50lb off my back.
First criticisms - I would give 5 stars if these two issues were fixed:
1) Should have some sort of rotating hip belt (it would only add a few ounces but make for a better fit after a long day of 10+ miles on the trail)
2) the buckles are too skeletonized (too thin). They are too thin and could break very easily. You could easily break them by stepping on them around camp, falling against a rock on the mountain, or even the first time I had to take this out with 50 pounds, when I unbuckled it the hip belt buckle caught and didn't cleanly release from the buckle, and if I didn't catch the 50 pounds with my arms, the one arm of the buckle surely would have snapped. Even though you can buy a replacement hip belt buckle (which is the most important) which is sturdier, you can't replace the other buckles on here since they are sewn in.
3) I wish it had a few more lash points to tie gear (hard foam sleeping pad) to, like on the bottom of the bag
1) carries heavy loads up to 40 pounds very well, and can carry loads up to 50 pounds pretty well
2) carries the weight nice and close to your back
3) the kangaroo pouch on the back is great although I wish it was a little more flexible to put more gear into
5) perfect size for me for weekend trips (the 40 would be too small)
6) easily compresses down to be a 35-40L bag with the side straps if you don't carry that much gear, but still gives you the flexibility to have a nearly 60L bag with the top fully stuffed.
7) moreso than other bags, the weight is loaded vertically and (depending on how much you compress with side straps) very tight against your back which I personally love since I hate hiking up some mountain totally hunched over to counterbalance some big ass weight on your back
9) has adjustable positioning where you can choose where the shoulder straps attach to the back, to accomodate large/small torsos
10) fits awesome
The bottom line is that it fits awesome. I am 5'11" and 170lb and normal lean/athletic body type, and I can't tell you how bad many other manufacturers fit.
I also got the Dueter ACT 32 this year and think that is a great fit as well.