First of all, if you plan to use this backpack as your "school backpack", you really need to get smarter.
That being said, this is a TACTICAL backback, it is not meant to carry books, or have a spot for your lunch and PE gear, no...
This little guy has just enough space for all of my emergency tools, extra medkit, quick-food (bars or MREs), and still has space for a notepad and extra mags/loaders I carry around the field.
Besides being a great asset in Airsoft, I have also used this pack as my "go bag" when I was out traveling: you leave your luggage at the hotel, pack his guy with "most needed" and go. It works great.
If you are having trouble accessing things you put in this backpack, you probably need to improve your organization skills. I have had some trouble, but when I have figured it out, there was no more.
Verdict: I want OD in stock, so I can get another one. =)
Little and comfortable. Even with lots of load, it is still sitting comfortable on my back.
If it ever gets trapped with your gear, there are enough release buckles to take it off.
Has space for a water bladder (there is a valcro almost on the back-padding, hard to stpo, but its there), but I think mine is too big for the bladder pouch.
Configurable to more or less stuff.
Access is a little complicated if you don't know how to pack, or your load is not organized. But when it is, easy to gain access to any tool, gadget, or item in the back, even if you have to ask your teammates to get it for you... as well as it is easy to describe which pocket this item is in: top small zip-pocket, or bottom medium zip-pocket.
The only con I found is that, when wearing my full load (and I have 12x10 esapi plates in my vest), it might be hard to hook/un-hook the chest buckle:
if you do it over your load, it potentially makes the bakpack sit "strange" on your back, and possibly obstruct some of your chest-mounted pouches.
To solve this problem easily, try putting the bucle UNDER the vest: I put the chest buckle belts under my shoulder straps and connect the bucle under my vest. There is just enough space and it also creates a little crack for some very much needed ventilation. Works great for me.
Otherwise, just don't use it.
Also, I would suggest not using the hip belt - taking it off from the start: unless you have no other gear on, it is almost impossible to use it, and then belts just hang lose and get you randomly trapped in vegetation.