We got this bag for our 5 year old who was off to school. It has been a huge success. A couple of key features which make it wonderful for a small kid:
1-- The over-flap on top means it doesn't have a zipper. The zipper is the part on cheap kids' packs that always fails. Zippers are also hard for kids to operate.
2-- The sternum strap means that the pack stays on rounded kid shoulders which is critical if s/he actually plans to walk with it on.
3-- The straps adjust so easily, that I can loosen them with two tugs and carry the pack for him.
4-- The external water pockets hold a wet, condensing water bottle away from school gear.