I have no child, yet (but I am in waiting), but I bought this game because I like simple, old school games.
I must say I amnot disappointed.
Hero Kids is an easy game, with good design ideas, a flexible resolution system and an excellent presentation (both the rules than the characters' sheet). The author put a great focus that you are going to play with young gamers, some of them aren't yet literate, so the game uses symbols and pics in places where other games use plain text (for example, for the stats, gear and so on). The game also includes a number of tactile elements as cardboard heroes, tiles for dungeons and so on.
As a parent, I would be worried about violence (after all heroes are bashing monsters in dungeons), but it is always on a cartoonish level: no gore, no blood, and absolutely no death. Monsters and heroes alike, when they reach 0 HP are simply "knocked out" and can be revived using potions, spells and rest.
On a pure-gamer perspective, I think this game could also be played from adults (the complexity level is more or less equal to Heroquest), and the fact that the heroes ARE actually kids, can give a different feeling to games (something like GRIMM, but more easy).
The only missing thing I see in this book is an advancement system: heroes don't grow in experience (but they can find extra gear), and in my experience, in a similar type of game it is essential: even very young gamers like their characters becoming bigger and stronger. It hasn't to be something ground shaking, even the chance to reroll a dice, to acquire a second special ability or to increase a stat is enough.
Overall a great game and a work of love, for rpgs and children.
[5 of 5 Stars!]