I am glad that you posted this because now I know that I'm not the only one who thinks that the ND games are hard
I have wondered about the age rating of 10 and up, too. Kids these days seem to get things pretty quickly, so maybe the games are easier for them than for those of us who are of "a certain age."
I know there was a discussion about it at Her Interactive but I really wish that the ND games had a "skip puzzle" option. I would probably be hitting it frequently!