Thecriticalcritics.com movie review on Unknown indicates that the movie is decent and enjoyable, but it doesn't get better than that. The movie review states that the screenplay of this film was written by Oliver Butcher and Stephen Cornwell and is quite amateur at certain points with dialogue that seems to be contrived. The movie is an adaptation of Didier Van Caulwert's novel, Out of My Head.
On the other hand, the movie review reports that Flavio Martinez Labiano's cinematography is very well done. The movie is wonderfully shot with apt locations. The movie review applauds the cinematography which has made the film less in-your-face that it could have been.
The movie review of 'Unknown' indicates that the film is an action flick that is not meant to be plausible or critically acclaimed, but is a good watch.