How to Train Your Dragon is the first good movie, that I've felt it was important to see in 3D to get the full effect. Up was my favorite movie of last year and I still don't think it needed to be in 3D it was perfect in 2D. Avatar was the opposite. In order to even mildly like the movie, you needed to have seen it in 3D. The movie was crap and the whole thing was really just a spectacle. Take out the 3D and you have a movie I like to call Pocahontas 3000. Cloudy with a Chance of Meatballs was OK, Final Destination 4 shouldn't even have been released, and Alice in Wonderland was worse than Avatar because the 3D didn't help make it a better movie at all.
How to Train Your Dragon is a mixed bag in terms of originality. First of all, it's not an original screenplay, the script is adapted from the book series by Cressida Cowell. I can't speak for the rest of the series, but the premise of the movie really is just E.T. with a dragon instead of alien. That being said, the characters are all unique and the scenery is relatively new to the animated world... I can't think of any other animated movies about vikings. Also... I want a dragon. Not just any dragon, I want Toothless. The scene where Hiccup is testing Toothless's boundaries and they are becoming friends was so heartwarming I almost threw up. Then, the friendship that they develop; risking their own lives to protect the other... I want a dragon.
I couldn't give a higher recommendation. I loved How to Train Your Dragon.