Picked the Sitka up from another site to be used as a streamlined day pack. After some use in varied settings I think that it's a good product with an innovative design and good features. For me, it needed a couple of mods to make it work.
1) One strap sling design:
Cool idea. I like being able to sling the sitka around if I need to. This feature works out REALLY well in both urban and back-country settings. Furthermore, putting the zips on one side is really smart, especially if you're counting on slinging the pack around a lot.
My only complaint with the sling design is weight capacity. With only one smaller stabilization strap you have to be REALLY careful with how much weight you put in the pack because too much weight throws it off balance and puts too much pressure on your left shoulder. Easy way around this? Throw a 1" strap on the tri-glide opposite the main strap and slide a fastex buckle on the end of your strap. Attach the other side of your fastex to the main strap close to where your smaller stabilizing strap hits and you're good to go. It adds an extra buckle but fixes your weight distribution problem.
2) H2O compatibility:
This is a great idea but, in my opinion, doesn't work well for the Sitka. The Sitka is just big enough to have a standard 100oz reservoir fit perfectly INSIDE the pack. Unfortunately, however, the H2O compartment was added as an outside sleeve that sits against your back. So it's possible to squeeze a reservoir in there...but it's pretty tight. Though it fits, carrying the thing around with a reservoir results in some serious sausage-ing which, again, throws your center of balance off. OK, so put a smaller reservoir in there. This works better than the 100oz, but you're still pushing the pack away from your back a lot.
Your call on this issue, I didn't like using the 100oz reservoir on the Sitka so I just use the Nalgene pocket for hydration now.
3) Extra pockets and such:
Great work here. There are way more pockets than I will ever use, but this is a pack (not a pouch) so they're justifiable. The added velcro is cool if you're carrying and the "Y" strap is usefull for holding your rain gear, so that's nice.
All things considered, I think the Sitka is great for urban use. It's do-able for small time back-country (unless you're adding it to a larger ruck system, which works well), but you have to be creative to get everything you need.