I came into this book knowing it wasn't quite like the movie, but that a great many people found it to be cute in its own right. And having read it, I think I agree. :)
Hiccup is the son of the chief of his viking tribe, which means a lot is expected of him. Unfortunately, despite him being a fairly clever and courageous young man, he can't quite measure up to the vikingness of some of his clanmates. And to make things worse, when he has to pick a dragon, as all young vikings must, he ends up with the most disagreeable, irritating dragon.
This book is adorable, cute and quick and just a plain fun read. The petulance of Toothless, the awkward friendship between Hiccup and his best friend, even the actually semi-serious ending made this entertaining and I highly recommend it if you're curious. :)