These are my quick impressions so far. I had the Bora 65, so expect a lot of comparisons with it. The Altra 65 is much lighter than the Bora. The weight savings are much appreciated. The pivoting hip belt seems to work as advertised, but I havent gone out yet in the field.The straps seem to have less padding than the Boras, but they are just as comfortable. Unlike the Bora, your back wont make contact with the entire back panel. It might make it cooler to wear. I havent played with the GridLoc shoulder straps, but they look pretty straight forward to customize. I like that not only can you make it longer/shorter, but also narrower/wider.
The fabric is thinner than the Boras, but doesnt look too thin or cheap. Unlike the Bora, the Altra doesnt have the ice axe loops or daisy chains. I never used them. All of this means more weight savings.
Things that are new: The U-zipper. I think its a great idea (I know some REI packs had it already). It makes it really easy to see everything in your pack. It is ideal for when your pack is flat on the ground. When the backpack is vertical, it works like any other zipper. The laminated zipper protector also doubles as a sleeping pad/tent carrier. I wouldve preferred a waterproof zipper rather than a zipper protector though. Obviously there is no sleeping bag compartment. I wont miss it.
Instead of compression straps it has compression wings. I actually like the idea. It makes it easier to secure a jacket. I dont use poles, so no idea if you can secure them with the wings. The Top lid has two zippers instead of one. The small one is "a map pocket." Not sure how much Ill use it.
The water bottle pockets are stretch mesh. Unlike the Boras, you dont put these away. I like the new ones better. The Altra addressed one of my wifes complaints. The hip belt now has pockets! You wont be able to fit much in there, and they dont have a zipper. They are perfect for an energy bar or two. Not sure I could fit a camera in there. In fact, I hadnt seen them until I read the specs prior to writing this :-)
Finally there is a proper hydration pocket. Unlike most backpacks, this one is off to the side. I couldnt fit in my 3L platypus filled, but a 2L one should fit. The water hose will come out on your right side.
To make a long story short, this is a great improvement on the Bora. You give up a waterproof zipper (hopefully not an issue) and axe loops and daisy chains. However, the trade off is well worth it.
PS The 65 does not have an occipital pocket, but the 62 does.