A fantastic, versatile pack. It can be big, it can be rugged, and it can be small.BIG - I flew from Kansas to Glacier National Park (GNP) with this pack and used it as a carry-on no problem, even though it was packed full with a week's worth of clothes, toiletries, books, and a few snacks. It was definitely full but if the straps are adjusted correctly, it doesn't feel heavier than a school backpack.RUGGED - I did a 4-day backpacking trip to Granite Park Chalet in GNP and pack performed like a champ. Rocks, weeds, sun, rain, it didn't matter. This pack was sturdier than I was at the end of those 4 days. Still have yet to try it camping, actually carrying my tent and sleeping bag in and out. I would expect it to be a piece of cake.SMALL - While in GNP I did a lot of day-hikes where the only items I needed were layers, snacks, and water. Even though the Kestrel has 48 liters, it's lightweight and can be compressed immensely flat against your back. I hardly noticed it even on longer and steeper trails.I cannot recommend this pack enough. It's great for hikers, carry-on friendly, and versatile in size. Plus, you'll look great wearing it.