Although Steve's character is a little hard to believe (a 17 year old with such a vast knowledge of gun use and no fear of anything-he's probably watched too many John Woo flicks as have the team who made the game) and he starts off the game as a bit of pain in the ass, but Steve's character may or may not grow on you.
Steve keeps his background a secret, and has trouble trusting people as he believes that he can't rely upon anyone else than himself. As he begins to trust Claire he begins to open up and stop being as much of a pain. This was where I eventually got over Steve's character as he began to properly open up, this was better character development than most RE games get, so I had to give him that much credit.
During the game you will even get the chance to play as him for a short stint. He also will try to help out Claire every once and a while, so he becomes more useful as the game goes on.