Watchable, but I wouldn't recommend springing for the pay-per-view, it should be on regular movie channels soon.
Rent-a-lesbian Cara Delevingne shows a few flashes of actual acting ability, but there's not enough time to flesh out the relationship between her and Dean Dehaan (Valerian) to make that subplot believable.
Gratuitous cameo by Rihanna feels gratuitous, as she seems to have been cast solely to have her and her body/dance double cgi morph into supposedly sexy outfits while performing a supposedly sexy pole dance for Valerian.
It's a hot mess of cgi overload. Seemed too busy for me. Maybe it just requires repeated viewings or knowledge of the source material.
*shrug*