Character Analysis
A Gamblin' Man
When we first see Eames he's in Mombasa gambling forged chips… in other words he's a dude who likes taking risks. He's a bad boy.
Eames does a good job of lightening the mood in an otherwise serious movie. We can't help but smile at his banter with Arthur and his general sarcasm. Every movie needs a jokester and Eames is definitely that guy.
Just because he's a bit silly doesn't mean he's stupid or incompetent, though. He is also a man of action and he's quite efficient when he jumps into the fray. He helps Cobb lose his tail in Mombasa and does plenty of shooting and blowing up in the first and third dream levels. Eames may not be a dynamic character but he certainly adds his own amusing layer to the film.
Shapeshifter Central
So Eames is a funny dude and a good shot, but he's also a forger: he first impersonates Browning and then a woman and then Browning one last time. This ability isn't only useful for distracting Fischer and starting the process of inception—it's also a reminder to the audience of what it means to dream.
In the real world, Eames is forging chips at a dinky bar, but in a dream he can be anything he wants to be.
While Nolan's take on dreams is a very structured one, Eames reminds us that we have the power to "dream a little bigger." Arthur may be good at bending our understanding of how things should work and creating paradoxes, but his technique is highly structured… even if that structure doesn't really make sense.
Eames, by comparison, is all about improvisation and thinking outside the box. While Arthur is shooting an assault rifle at the baddies in dream Level #1, Eames pulls out a grenade launcher and makes quick work of them (we're not going to get too technical about whether or not non-dreamers can conjure objects in the dream world; we'll just accept the scene with its creativity and levity in the spirit of Eames).