I was skeptical about this pack. I'm a die hard osprey user and have been for years. When they released the new designs I was hesitant. You know the why change something that works mentality. Well let me tell you this pack was amazing the right size for fastpacking and all the right compartments for storage right where you want them. It's a little sad now because I want to update my 2L and 7L packs to the new design too! Similarly this is the perfect sized pack for fastpacking. The adjustable weight belt isn't necessary if you aren't running but when you need to pick up the pace it's nice to be able to buckle down. 2.5 Liters of water is a lot to carry on your back and makes the pack heavy but it is nice to have the option and as you drink more and more you can keep adjusting the arm straps tighter and tighter so the pack never looses its snug fit. I wore this recently on a 5 day traverse of the GR20. Wouldn't have changed a thing! Nice to be able to find a pack that fits small enough. I got the XS and I'm 5'8" and 120 pounds.