Callan Bond’s review published on Letterboxd :
Decent French procedural-thriller. Cassels and Reno are both solid as cops whose cases come together into one as a hunt for serial killer.
Shot very well and makes great use of a variety of locations and seasonal changes, from autumn in the French countryside, to sleet during a foot chase, to heavy snow, to Reno exploring an ice cave inside a glacier. There are also some good tense "chase-the-killer" sequences and interesting CSI~esque lab discoveries, both obviously influenced by Se7en but done well here.
On the down side, the plot is wayyy overly convoluted, and I still didn't have a decent grasp on everything by the end. There are also a couple of minor plot leaps where I didn't get why the detectives suddenly knew to go to location 'A' or interrogate person 'B'. Lastly, there's a weird kung-fu action sequence that comes out of nowhere and then ends up having nothing to do with the rest of the movie.
Not a bad flick, certainly watchable, but not as good as I remember when I first saw it in the early 2000s.