I watched it yesterday. Great visual design that worths seeing on a big sceen, although nothing groundbreaking that I didn't see before. The CGI was a little obvious but it didn't bother me and the aliens that were made practically looked great. From the design it was obvious the movie comes from the same place The Fifth Element came from.
The movie falls in the script. The world building is good and I loved the opening credits scene, but the plot is weak and the constant divergences hurt the main story line. The biggest problem of the movie is the dialogs, especially between Valerian and Laureline, which were terrible. The dialogs regarding the relashionship between them was cliched and very heavy handed. However, while Valerian is an unlikable character in general, Laureline is great when she's by herself and the best thing in the movie after the visual design. Good work by Cara Delevingne. The movie indeed should have been called Laureline and the City of a Thousand Planets.
All in all it's a mediocre film but worths watching if you want to see some cool science fiction visuals.