Seems like a sturdy enough and comfortable to wear backpack for traveling (not backpacking). I plan on taking it to europe so will see how it performs. The interior is just as deep/wide as my luggage on rollers but I think this will be better for going off and on trains etc. My only concern is safety - hoping it will be theft resistant as well although it is not like pac safe bag. Osprey seems like a well made product overall.

August 2012 Update: I took this moderately sized backpack through 4 countries, on trains and planes in overhead and it worked fantastic! It was the perfect size for everthing I needed (except for carrying all the knickknacks I bought which had to be shipped home). But if you are looking for a sturdy traveling backpack, definitely consider this one. In terms of safety, I found a way to use a lock on it so that no one could open it up while on my back (because the zippers are not lock proof). It worked great. And the times when I was waiting around, I just kept my back and backpack toward/against a wall. Can't wait to use again on my next trip!

August 2014 UPDATE: I still have this backpack and used for my trip to new zealand and sydney australia and it held up great. It may not be *the* most comfortable in terms of shoulder straps while walking a long distance, but I have to say I still love it. Very sturdy, secure, great buy.