This movie was good, but I have a few problems with it. Overall, it was probably a bit intense for little kids, but otherwise wonderful. My issues with it lie deeper than that.
I enjoyed the fact that it played off of Irish culture, history, and fables, but it wasn't entirely accurate. One little thing I picked up was that most of the characters are redheads, but they fear the coming of the Vikings. Historically, the "typical" Irish red hair came from the Vikings, which would make it impossible for the movie characters to have red hair before their arrival. This doesn't make it a bad movie, I'm just nit-picking.
One more significant problem is that I think it ends too early. The story is hardly resolved. The last few years of the story are summed up in a couple of minutes, which I thought did it little justice. Not to mention my favorite character, the spirit girl, is under used. I'd have like to have seen more of her.
Despite my review so far, which I feel I should apologize for, the movie is beautiful. It's filled with gorgeous imagery, and the music is enchanting. See this film, and enjoy the fantasy of the Book of Kells. I also suggest looking up the real thing; incredible.