I took this bag on a trip to Germany; it survived airplanes, trains, buses, and hikes to youth hostels. I tend to be very hard on my equipment, but I was still a bit disappointed that the bottom parts started to fray after the first week - nothing to compromise the sturdiness of the bag, but still, not visually pleasing.
Other than that, the bag fulfilled and even exceeded my expectations. It can be very easily wheeled with the day pack attached by the zipper, or carried by the top or side handle.
When boarding the airplane, it meets the requirements for one large (big bag) item and one small bag (day pack); just detach the day pack and carry it either by its backpack straps or attach it to the handle - it has a horizontal strap for that purpose. I usually pack items for the first few days in the big bag and then items for the flight (books, mp3 player, first aid kit, etc.) in the day pack. The large bag fit into the overhead bin, and the day pack under the seat in front of me with room to spare.
The day pack has several neat pouches in the front which make it easy to quickly find pens, electronics, etc. There are also two side meshes on the day pack which hold average size water bottles.
The large bag has plenty of space for clothes and other items. Even my large camera bag fit in there nicely. I did not try the backpack straps for the large bag, simply because I tend to stuff so much in there that it would have been too heavy to carry on my back, but they look sturdy enough.
The product was perfect for my purposes. I did not take my laptop this time, so it was not an issue, but when I do, I probably will not use this bag, since there is no compartment for it. Other than that, I highly recommend it.