I think people expected more intelligent story telling from this movie after how interesting district 9 is. It's definitely not nearly as smart of a movie, but I still liked it a lot.
Matt Damon and Sharlto Copley are great, they interacted well, the technology was cool, especially to see the division between the on the ground tech and the in the sky tech, how much shinier and such the Elysium robots and crazy rail gun thing were.