I have been debating on buying this for a while.  I just couldn't decide if it was going to be too small, but I got it on a sale site for half price and just couldn't pass it.  My son is going into Pre-K, and it WILL hold a normal 8 X 11 folder, BUT you have to smash the corners in. It's plenty deep, but not tall.  I'm planning on putting spare clothes in the front (insulated part) because our school required spare clothes just in case :) The shoulder straps are actually quite large (for a parent using it as a diaper bag is my guess, but it makes the strings super long to tighten them for my son. The zipper is super smooth gliding and it really feels like an amazing prodcut! My son was not sure the first few times he saw it on line...but when we got it (we got the space one!) he will hardly take it off!  He LOVES the buckle across the front, so it won't fall off (he does all sorts of punching just to test it!) Since getting it he can hardly wait for school :)  AND FYI!! I contacted O3, and they said to check back in 2013 for bigger sizes, that they are working on it!  I love that they were so prompt in responding to me (even on something random, not an issue with an order!!)  So far I am more then impressed this this item!

UPDATE! 5/20/2013
My son has used his backpack all school year, and taken it to stay the night...it shows NO wear at all!  The white is looking dingy, and I'm going to have to throw it in the wash...but it held up better then I ever expected!  Great job on a great product O3!