Above Average. Nice episode for Kate (for a change).
The scene where Sawyer and Kate turn lil Ben over to Richard despite the warning was creeeepy as hell...
But I don't think the writers needed to give lil Ben amnesia. I don't recall any point at which he "should" have revealed he already knew the Losties. It would have given him more power over them not to reveal that, and he always had that "I know more than you do" aura about him.
But it seems like Jack's indifference to helping Ben is what created Evil Ben.
If Jack saved lil Ben, something else would have made him evil. Jack's speech to Juliet about the island doing what the frak the island wants to do says to me that he's starting to grasp the "rules."