This is a very thoughtfully-designed backpack.  I always strive to do carry-on only, and this lets me max out my allowed space and easily transport my stuff.  The pockets were all useful in their own way as was the water bottle holder.  The waist belt got sort of a "meh" from me as I didn't find it to be as functional as the waist belt in a true backpacking pack; it didn't support much weight in the vertical direction.