Vincenzo Natali, of Cube fame, and was what really put his name on the map.
And like so many of the others I've mentioned here on this site, it is a multi-layered film.
On the surface it is simply your every-day big corporation spy-thriller; much like Blade Runner was simply a detective story about a guy struggling with his femme fatale.
Of course, these stories are just soapboxes for the characters condemned within them to grow, and what they learn along the way is what really makes the films great.
While Blade Runner could be considered an intellectual study of what it is that defines humanity, the secret combination to Cypher holds underlying themes of what defines character, personality, how we see ourselves, and who we want to be.
The ending is probably predictable to most movie lovers, but that doesn't matter. The existential ideas presented along the way are more than enough to give you food for thought, for a long time ahead.