Was there a point to the Sawyer backstory? Didn't we already know that he was a con artist?
I agree with Dafones: a better question might have been, "Didn't we already know that Sawyer was a big jerk?" The answer is yes, but we were also ready to forget all about that because he's also charismatic, funny, and been through some really terrible times lately.
Sawyer has lived his entire life under the belief that he deserves to be mistrusted and hated, so does things to make sure that he is. It goes back a lot farther than the guilt he feels over the things he's done: Sawyer hates his father for being so gullible, stupid, and weak, getting conned and commiting suicide, so he's devoted his life to becoming a predator himself. He believes himself to be irredeemably corrupt, despite the fact that his conscience drives him to push everyone else away so that he can't take advantage of them.
A sociopathic con artist has it easy. Sawyer does not.
However, the background story on Sawyer was good if a bit shallow. I'd like to see a bit more dynamics come through in his back story...he's too charismatic and sinister to be that one dimensional.
I'm prepared to agree to disagree about this, but "one dimensional" is just about the very last adjective I would have used to describe Sawyer.