I just returned from a 2 month trip to Indonesia, and before I left I looked long and hard for the optimal travel backpack. This backpack served well for my purposes (we were on a surf trip and got around via scooters and taxis), but it is not the most ideal backpacker's backpack.
I like the luggage style, full-frontal zip opening which allows you to open the backpack fully instead of having to dig through from the top. The better access allows you to keep things organized as well as reach everything much more easily. The bottom portion of the bag can be separated into an isolated, smaller compartment, which I found to be useful (I put my toiletries in this bottom area).
It is also great that you can zip up the main straps/frame area with a cover (that folds into the bottom of the backpack when not in use) so they don't get damaged when traveling on planes, etc.
It is really nice to have a smaller, removable backpack and I used it more than I imagined I would. However, the downside to it is it's a bare-bones little backpack with no features. It is on the smaller side too, which worked fine for me (it fit a towel, small waterbottle, sunblock, and a book alright but I don't think it could squeeze in much more). If you planned to do some long day trip missions this little guy probably wouldn't work very well.
What I did not like about the bag is the shoulder straps when you actually have the bag on. They sit very awkwardly. What the problem is is the straps that attach the backpack to the shoulder straps do not stay tight and constantly come loose. This in turn makes the bag pull away from your body up at the top of the pack which is very uncomfortable. For my sake we didn't do a ton of walking and or trekking with our packs on so it wasn't to much of an issue; however, if you are planning to put in some miles on your feet with your pack on this would become a major, major problem. We never figured out a way to resolve the problem.
All in all the backpack is pretty good and worked rather well for my circumstances, but it really depends on what your purpose for the pack is. If I was doing any kind of trip where a fair amount of walking with it on was necessary I don't think I would have liked it as much.