Beckman is a tall man, standing at least a foot taller than Shanks. His hair was jet black and pulled back in a pony tail 12 years ago in Monkey D. Luffy's hometown; in the current storyline, his hair has turned gray and is cut short. He is never seen without his rifle nearby or a cigarette in his mouth. He also now has a large, X-shaped scar on his left temple.
Beckman appears to be a lot less fun-loving and a lot more relaxed than the other members of the crew are, acting as the level-headed member. He, Lucky Roo, and Yasopp are some of Shanks's most trusted crew members, as they are always seen when the Red Hair Pirates are featured, usually when something crucial happens.
According to Oda, Beckman has the highest IQ of all the characters introduced in the East Blue saga. Since he is a first mate to a Yonko, he presumably possesses a great deal of strength. During the Battle of Marineford, Admiral Kizaru chose not to fight him, even though he had just fought the First Commander of Whitebeard's crew and Whitebeard himself. It should be noted that Kizaru did, however, continue his attack on Luffy when Beckman came down to join the rest of the crew.
(Source: One Piece Wikia)