This is a really tough one to rate... There's a lot of good here, but some clunky bits as well. On the positive side, it has absolutely beautiful special effects, creative designs, and an awesome world(s) full of unique creatures and alien life, concepts, and action. In 3D it was a visual feast.
But on the other hand, there was some really awkward acting when you first meet the main characters. Cringe-inducing stuff, literally. But as the movie goes on performances gets better. The story was very predictable, and there is alot of inconsistencies. Is Valerian a wild reckless agent, or is he a by-the-book agent? The movie would try to have it both ways when the resolve the main conflict in the film.
But overall it was a fun journey with amazing visuals. I would recommend it for the FX alone.