No spoilers in this post.
I saw this in 2D. While I don't like paying more for 3D or wearing glasses for an entire 3D movie, there is something I do like about 3D. When a movie is designed in 3D, it feels like they pay more attention to movement. So even in 2D, the movie feels more exhilarating. This was definitely true in How to Train Your Dragon. This was a fantastic movie, probably the best one I've seen all year so far. The characters are endearing and you become invested in them right away. The plot is fairly conventional, but there were a few developments that I didn't expect. The best part of the movie are the emotional moments. Because you care about the characters and because the film is beautifully crafted, the moments of discovery or insight or betrayal are very compelling and powerful. I highly recommend this movie.