Pitof's style and design comes blazing through, in a kind of high-octane version of the work he did for Jeunet & Caro - a mixture of French garishness and Tim-Burton-esque gothic fantasy and detail. Also reminded me a bit of Alex Proyas' design on Dark City.
The plot gallops along, with Depardieu appearing in flashback scenes throughout while his biographer, the police, a decadent journalist and his sidekick all try to re-trace his steps, solve the bizarre murders and capture the Alchemist (if he or she even exists)!
There's so much going on on-screen that it's a complete feast for the eyes, especially once femme fatale Preah gets mixed up in the mystery.
I also thought it was so refreshing to see the investigative duo of Vidocq and Nimier, because they are both coarse, brainy & brawny (like two bears in top hats), whereas any Hollywood film would surely add numerous physical & character defects. You'd also lose the wonderful surreal Frenchness of the setting, and almost grotesque supporting characters.
The Alchemist is a great baddie - not superhuman, but you're not quite sure (for a long time anyway) if he/she is really supernatural or not - or of his/her motivation, and by the last half hour you think it could be virtually any of the main characters under the mask, which sets you up for a really good revelation or two & a battle at the end.
An exciting movie (complex, but not difficult), and not one dull moment. I'm not sure what some of the negative reviewers were watching, because if you liked Sleepy Hollow or From Hell, you'll adore this.