Saw the film earlier, in 3D.
The good: visually maybe one of the best films made since CG effects became a thing - a lot of moments where I knew I logically had to be looking at something CG, but my brain refused to believe it wasn't real. Weta did amazing work here. There's some great cameos by big-name actors. Everything moves along at a good pace despite the 2.5 hour runtime. Some utterly stunning worldbuilding and designs, many of which really deserve to be made into toys and statues.
The bad: Cara Delevingne surprised me by being a lot better than I expected as Laureline, but that's not to say she's good - has nowhere near the charisma or presence of a young Milla Jovovich in Fifth Element. Dane DeHaan, sorry to say, is just wrong for Valerian - his attempts to be a cocky old-fashioned action man come off as annoying more often than they do endearing. The thing that probably hurts the film the most in my opinion, a very weak villain who's barely-present - this film was crying out for a Zorg-type character and an actor of Gary Oldman's abilities to portray them. Doesn't have any of the creative, fast-paced interweaving editing of Fifth Element either. Wastes the amazing Rutger Hauer in a one-scene talking-head cameo early in the film.
Overall I'd say a solid 6.5/10 of a film that manages, for a few scenes at least, to recapture some of the Eurocomic vibe that made Fifth Element so much fun. It's annoying to consider how much better this could have been with more appropriate casting for the protagonists, a stronger villain, and better editing though. It's so close to being something great but never quite makes it across the line. I don't think it deserves to have crashed and burned as spectacularly as it has, however.
...a visual feast, and the 3D was amazing. 
...If they ever see the light of day. 
