The evolving relationship between Rose and Sarah Jane was gorgeous - from the initial jealousy and bitching to their togetherness at the end. Sarah Jane having to face up to moving on, Rose having to face that the Doctor has a past and she is not his first companion. Lovely stuff.
Te Doctor's talk with Finch by the pool was fascinating. "If I don't like it, it will stop." There is so a great fall coming for him in the future. The whole chemistry between Finch and the Doctor throughout the episode was amazing - I don't normally hope for villians who seem fairly obviously killed off to come back, but for Finch and ASH, I'd definitely make an exception.
And the dialogue had several beauties that will be quoted for years.
"I can't believe it's you."
"Now, I can."
And ASH frigging rocked.