Specs are quantitative aspects of the option such as the price
Pros
Pro
Easily access your hard-to-reach things
You can access the bottom of the bag by opening a zipped front pocket (at the part which touches your back when you're wearing the bag). This eliminates digging around or emptying the bag out when the stuff you need are at the bottom.
Does not restrict you to use both your hands when rummaging through the bag
The main opening holds itself open. This allows for you to easily dig through your things with both hands and not hold the flap open with one hand like how other bags are.
The main opening's zipper cannot be opened and closed using one-hand. Although it runs smoothly, there are angles at the bag's edges that requires you to hold the bag steady with one hand while zippering.