Strongly constructed. The couple dozen pockets do much to keep things organized. I've had this backpack a month, and find it far superior to anything else I've seen in 20 years. The only weakness I've seen may be that the bottom of the backpack is not noticeably reinforced, but it may not need to be. The only reason I'm giving it a 4 vs a 5 is I haven't (yet) had it long enough to assess its longevity over several years, but I suspect will pass that test, too.