My kindergarten son uses this bag.  I imagine it is a good size up to 2nd grade. After that age, it wouldn't look right.

Pros--
High quality materials, different cloth is used and stitched together to make Scooby soft.
2 pockets on front, and full large compartment as well.
Comes with small water bottle and pouch on side.
Other kids will notice this bag.

Cons--
Just for early elementary school years. (too large for preschool)

Moral of the story--
The perfect school bag for early elementary school aged kids who like Scooby Doo.