Great idea! I made one similar a year or so ago (seen here). The one pocket was extra large an hung off the side. I made another for a friend that had maybe 3 pockets on the side but didn't hang off like the large orange one in the pictures. Anyway, nicely done.
I really like your design. Putting stuff inside that bag and digging it out could be a pain. The outside pockets are a must. Things that can be put away til morning would be good for inside the sack and books, ipods, etc for the out side vertical pockets. I make some similar to yours, except out of bugnet material.