I have used the product for backpacking trips. I carried it on a fourteen day vacation through Egypt, Jordan, and Israel/Palestine. I had plenty of room in the bag after packing to even pick up a few things along the way. On this trip I had to do a lot of walking around and found no discomfort with the bag, it has a nice weight distribution that takes the strain off of your shoulders. It was much easier to carry on trips than it would have been to drag a suitcase along.
The small attachment bag was also very useful. I could leave the big bag at the hostel/hotel, while carrying the small one with my SLR camera, small camera, water, map, book, and a few extras around in the city or through the mountains all day.
Two of my travel friends also carried this bag and we all found that it was ideal for our backpacking trip.

I bought this pack after 6 months trolling around sub saharan Africa. I'd selected some wheeled equipment for that trip, regretted it and thus went looking for a shoulder-borne option.
Its first trip was a combo of 1 week in Belize and 1 week in NYC. The front loading 85 liter size was more than adequate to the huge amount of clothing necessitated by these back-to-back disparate locations. The fully adjustable rig allowed for complete comfort throughout and the rain cover was truly handy both in the weather and on the luggage conveyer belt.
The biggest surprise of this setup was the utility of the day-pack. It was just as at home carrying my snorkel and mask in Belize as it was my DSLR camera in Central Park. The best part was how securely it stowed to the main pack for transit once the day trips were done.
The Grand Tour 85 is a great value if you're looking for a bag aimed at satisfying travel needs.

Purchased this item to substitute a regular suitcase for deploying into Afghanistan
It would be great for short weekends
Not so great for traveling when more room is needed for clothes and equipment
Will unfortunately return this item - did not meet my specific needs