The Informers is a story of various upper class individuals and their disconnect with themselves and others. Featuring a large ensemble of characters and the usual cynical tone of writer Bret Easton Ellis, it takes a lot of time to know the character well enough to even care, and character development is probably not as great as it could have been.
If you a big fan of the author's body of work (his novels or their adaptations) you may as a completist make an extra effort to enjoy this but aside from two or three memorable moments, such as the conclusion, things are rather flat.
Director Gregor Jordan's filmography is getting progressively worse since the amazing Two Hands, which was made back when he had little money to work with, away from big Hollywood influences. Here, he fails to provide any structure. Only the pacing and tone remain consistent.
There is a sense that the screenplay adaptation (by Ellis himself) butchered his novel and a sense that the producers further butchered the screenplay. Actors parts (Brandon Routh) were completely cut and this movie must have been an editing nightmare. Overall, it was probably too late to scrap that one but I strongly suspect the only reason it got made in the end is because of many people who are fans of the writer and his work.
The problem is, outside of American Psycho, none of his novels has translated very well to the big screen. Probably time to appreciate his writing in novel form and forget about films.