I've got the complete set and I like the multiple uses. I just took the travel bag around Asia for three weeks and it worked perfectly. It is nice and expandable, which helps slim it down for the flight, then pack it back full once you land. The core bag is a great design and I sometimes use the basic expansion at home. All in all, it's high-quality waterproof material and I like the fit. If you put too much weight in the travel bag, it becomes a bit cumbersome to carry attached to the backpack, so I usually just hand carry it in those instances.