I really enjoyed this. I don't usually like cross-dressing, but the garters and stockings were a nice touch, and I like bottom!Snape. I loved the talking during sex. Sometimes I wonder if people who write sex scenes believe there's always a format to be followed, such as only non-speech sounds, like moans and groans, and laughing it not allowed because sex is srs buznes. So I liked the conversational tone even in the midst of intimate activities.
I did think, though, that the end was a little unexpected. I like fluff, but given that Snape and Harry handn't seen each other in a while and hadn't had many favorable interactions before, I was suprised that they were already discussing entering into a relationship.