It's a movie by Robert Zemeckis inspired by and old english epic poem titled Beowulf (the name of the hero) but to save me the explanations there are some links:
the movie's page
http://www.beowulfmovie.com/
and two links from wiki about the origins of Beowulf
http://en.wikipedia.org/wiki/Beowulf
http://en.wikipedia.org/wiki/Beowulf_%28hero%29
The movie is animation but all the main caracter are played by real actors by the performance capture technique and render on screen by animation. And many times in the movie the characters seems almost real. It's very well done. The movie is presented in standard format and in imax 3D. And if you want to see Angelina Jolie in 3D ....
There will be competition for the Oscars concerning special effects TF movie no more alone.