Okay, firstly, I loooove the shadowing. I'm such a sucker for good shadowing. Hee!
Similarly, the subtle patterns in both their robes, and the tablecloth. Gorgeous little bits of texture. :D
I love the way Harry's just concentrating so hard, and Severus looks so indulgent. <3
Aaand finally, I like the way Harry's robe looks more like an over-robe+shrug sort of thing; my imagination makes what he's wearing under it much more racy. Bwaaaahahaha. :D