Thank you for sharing. That is certainly an interesting choice.
Many of those reviews on the first couple of pages were from people who seemed like they were normal vacationers, and not actual backpackers on the fly, in which case this pack will work fine.
The hip straps look non-existent on this pack. Sure, it will secure the pack to your body, but they won't do anything in terms of weight distribution... and that is a major key playa so your shoulders and upper back don't do all of the work.
As far as walking is concerned. I have found that I have always done a lot more walking with my backpack then I imagined. Forget hiking. City walking with you pack to and from airports, train stations, hostels, bus stations, metros, searching for accommodations and all the other stuff I mentioned, etc...is enough to wear you down. If you don't have hostel reservations in any or some of the cities that you're going to, and plan on walking around to look for some "when you get into town," then you can find yourself walking for a good long time.
And when you do find yourself walking for hours with a fully packed backpack, your back will get sweaty. That's where the padded spinal column comes in handy, which usually comes in backpacks with internal frames.
I'm not sure where you're going, your transportation plans, and for how long you're going, but definitely practice walking around with it, fully packed, for a few hours or days
to be extra sure that it will fill your needs. Don't cheat on practicing!
Not trying to scare you. Just my 2 cents.
Hope it works out for you