I purchased this for a trip to Europe and have been taking it with me on day trips to Disney to get a feel for it and its capacity.  I am carrying a packable hiking jacket, a superzoom camera, a journal, an iPad with keyboard, a tripod and a bottle of water.  It all fits very nicely and the special locking zippers keep it all very secure.

The issue is weight distribution.  When the bag is loaded the thin straps take up residence in my armpits which is rather uncomfortable.  The model above this one and all the others include a chest strap that distributes the weight more evenly.  If this had that I think it would be perfect.