Depp, especially as of late, is well known for portraying characters that are larger than life or eccentric (especially with the 'Pirates' films). One would expect something similar in his appraoch to personify an infamous bank robber during the Great Depression, but surprisingly Depp is reserved and understated as Dilinger. Depp's performance shows a small range of emotion and very intentional when he shows glimpses of softness. One of very few smiles he cracks is when he lavishes his new girl with a new fur coat. His other smirks are much more self aware and relaxed, including his pleased look while watching a news update about himself at the cinema. Depp keeps scenes interesting because he holds so much back. The character he created is appreciated in subtleties and glances and is never heavy handed.
Christian Bale offers a similar performance as the FBI (near the Bureau's inception) agent who is set to the task of apprehending Dilinger. He is similar to Dilinger in that his one driving force is in trying to catch Dilinger, but unfortunately we don't get to see how much this character is effected by Dilinger because we see so little of him. This is one of my biggest complaints with the film - the painful under use of Christian Bale. In watching the film progress there is a longing to see deeper sides of Bale's character, to know the complexities and conflicts he has, but there is no payoff in this area which is a shame.
One disclaimer to all is that this quality film is being horrendously mismarketed as the action movie event of the summer which it certainly is not. The 4th of July weekend is even misleading as this film does not mesh with fighting robots and other fare this time of year has to offer. I am afraid that this film will not be well received and that is not because of it's quality but because it didn't meet the viewers expectations. Many will also be turned off by the style as it was shot on digital video as opposed to film. The tight, shaky camera seems appropriate and makes the film seem more personal but it does seem modern for a period piece and that can take the audience out of the story. While the film is a little overlong and does not flesh out the supporting characters well it is still a very fine film, one of the better ones I've seen in recent weeks, and with proper expectations most will find something to appreciate about it as well.
Final word - 8/10