Since the game is not yet released there is very little information on the game, even at the publisher's website. Like other thinkSMART games the game will have 3 levels of difficulty (Easy, Medium and Hard). There are also hints and an undo feature.
If your five year old can comprehend the basics of chess, they should have no problems. On the other hand, if your five year old has trouble counting and thinks potato comes after two, they may need an easier game... or better yet quality time with their parental unit vs being handed a DS and shoved into a corner. :]