The animation is excellent, the story interesting, the basic idea pretty novel, and the characters lovable. They were even able to insert a pretty dramatic and heart wrenching scene as well as a hero finish. You can't ask for much else.
It's an all around excellent animation film, and if you're even slightly interested in video games, especially those old 8-bits ones as well as how it all evolved and the different types of games, you'll be in heaven.
Go see it on the big screen.