My six-year-old and I just spent 2 weeks with Hiccup the Useless and his Dragon Toothless. We'd picked up the book after we saw an ad for the upcoming movie.
Now I'm not sure I'll bother seeing the movie-- the book was hilarious, and I'm afraid the movie will be a let-down. But we're definitely picking up the rest of this series. Hiccup's adventures were funny AND exciting - my daughter couldn't get enough of them and is still talking about Hiccup and Toothless. I can't believe I missed this series when it first came out!