My daughter began playing this game at age 6.  She will now play it with anyone who offers!  It is challenging and fun for adults as well.  The only downsides are that you need a fairly large, flat surface to create the tile patterns, and you need to be prepared to play for 30 minutes or more in order to finish a full game.  If you bump the table and jar the tiles, it can really lead to chaos if the game is fairly far-along.  Overall, however, I highly recommend it, even for adults.