Delightful! So many have said so much that I feel I am only repeating their praise in a poor manner, but... why not?
The coffee girl is, of course, the best. I love that even though he is annoyed, he still comes back. Maybe it is the only decent coffee around, but I think not.
Being a Snape exchange, I figured it was Snape, but you know? I found myself not caring. You wove the story with such charm and skill, that if Benjamin had just been Benjamin, it would have been fine with me. Perhaps because it was fine with Slughorn, too. The fact that he was willing to drink the potion because it might gave him better odds at seeing Benjamin again was really quite touching, and spoke volumes about his feelings for not just Benjamin, but Snape as well.
I love that it was Poppy who wove the glamour for him - she always did strike me as someone who was fiercely protective of her students, especially the ones that were the most emotionally vulnerable. And the stone? Perhaps done by Filch, but tucked away among the herbs, a tribute so very personal, made me tear up.
And Snape's remark about stealing his gift on the way out was so... Snape-like.