Idea taken off BioWare forum.
Me, I will remember him as an extremely wickedly cool renegade Shepard. Now, he definitely wasn't a saint. Destroying hundreds of innocent lives just for a diversion. I do not, however, think that he was ever truly evil. He merely took the entire "the ends justify the means" thing a little too far. A little like Jack Bauer, but he's willing to go a whole lot further. Bauer wouldn't directly harm an innocent unless he had no better choice, I think.
He was indoctrinated. Okay, he looks like a total ass if you don't charm or intimidate him at the end of the game. But if you do, he thanks you and shoots himself in the head, which is still to me the second best scene in the Mass Effect series. The first being when he attacked you on Virmire.
So, what will you remember him as?