First, let me thank Osprey publicly for allowing the BPL community the opportunity to review this pack.
I'll try to add to, rather than repeat what has been said to date.
Water drainage:
I just swam around in my pool with the pack on. When I got out the two holes were functional, but I was getting just about as much water loss from the seams. I'd have preferred to dump the water out than wait for the two holes to drain the pack.
Having said that, I had only three water bottles in the pack, so quite a bit of water was allowed to get in. My sense is under normal conditions (the pack full) that less water could get in and the two holes would be sufficient.
The trade off is that a larger diameter grommet would allow dirt/mud, etc. to enter the pack when it is set on the ground. So, if taking on water is a frequent occurrence you may be disappointed. If it is infrequent, the pack will please you.
Suspension:
I have the sense my pack is too short in the torso, I would probably not have bought this size of pack. But, the suspension system seems to work, at least 17.3 lbs on a short hike this afternoon felt just fine.
If the suspension was larger for my torso, the pack could be larger than it is. However, I'm concerned if the pack was larger and carried more, it might overwhelm this suspension design.
Packbag:
I like it. The compression straps are functional and don't interfere with the side mesh pockets. The lid carries a rain jacket; it is removable, but I can't see myself being so weight conscious. The side mesh pockets will carry a lot of wet stuff until it dries (socks, tarp, raincoat), although one's water bottle may not be accessible while the pack is worn because the pocket is so deep, it extends the length of the pack. The hip belt pockets are mesh, so you'd want a dustproof/waterproof camera and a way to keep your half eaten gorp/energy bar out of the dirt. The hip belt pockets are not easy to reach and get into because they are behind and out of easy sight.
My hike today was in very hot and humid weather. The mesh and foam backing were reasonably well ventilated.
Quality of workmanship:
My quick test of any pack's durability is the haul loop; it feels very secure. I didn't see any flaws in this pack. The quality would not disappoint a gear picky BPLer.
In sum, if the pack fits you I would recommend it for loads and purposes for which it was designed.