Honestly it is the best film adaptation of a Shakespeare play that I've seen. Seriously, it is gripping in a completely unexpected way.
The interesting thing is that the way this movie recast the play as a modern political and military drama/thriller works better than most and it would be an interesting way to approach a modern thriller that wasn't based on Shakespeare or some other classical piece of literature. That short lived series KINGS sorta did something similar with the story of David, but not nearly as well.
The only thing that holds Coriolanus back is that though it is very, very well edited to deliver the most understandable bits, the dialog is still straight out of Shakespeare and though beautiful, it really takes an exhausting amount of concentration to keep up.
Still, for the most part, the directing visually communicates the story. Feinnes did an excellent bit of work all around for this.
My favourite Shakespeare adaptations are probably Kurosawa's Throne of Blood and Ran, Branagh's Hamlet, and Orson Welles' The Chimes At Midnight. But Coriolanus was great. I wouldn't have guessed it was by a first time director if I didn't know.
I have never seen any kind of production of Coriolanus before or read the text so I don't know what the character is like in other hands, but in Fiennes' hands he was very compelling. His mix of contempt, aloneness and extreme humility made for a fascinating character. He felt modern and relatable.
Brian Cox and Vanessa Redgrave were fantastic also.