This is an OK bag, and only a few oversights are keeping it from being great. Thicker backpack straps with a mesh foam back cushion would make it truly usable as a backpack.
The mesh "lid" in the main compartment should have its zipper direction reversed, so that the inside could be reached from the top without split opening the whole bag, when in backpack mode.
It would be better to move the main zipper more to the front of the bag, so that the bulk of the bag is solidly attached to the rear and only a thin lid in the front opens up. This would also allow the bag to split open without undoing the backpack straps AND enable another spot for a small pocket for various items on the top (fleece lined sunglass pocket for example). Furthermore, this would allow the opening of the bag when its placed on its back on the ground instead of front-down, as it is now.
Currently the two only pockets will generally be occupied by clothes/shoes and a liquid baggy for airport security checks, leaving no empty easy access pockets for a water bottle, umbrella or anything else picked up on the way. The main compartment also needs tie-down straps.
With Thule it seems that you pay for the quality, rather than the feature set. The straps are solidly sewn onto nylon webbing, all zippers and seams are done well, the bag really feels like a quality item. But really basic oversights, like no tie down straps in the main compartment, no simple pocket for extra stuff picked up along the way (i.e. water bottles) make you really question if it's worth the high price.
Would I recommend this as a simple grown up shoulder bag? Yes. Would I recommend it as a feature rich bag/backpack combo for everyone? No