I was absolutely LOVING the episode until the very last second. Denny and his 'are you sure?' was RIDICULOUS and beyond IDIOTIC. I hated that, Shonda really has found a way to RUIN the magic between Izzie and Denny, and it's not even clear if she did that on purpose.
About Hahn, from a medical logic, I totally understand her. But since I'm 100% passional about this, then **** her.
I think they managed to find a good way to get rid of Erica, but I think there should have been a scene with her saying "I quit", "I'm leaving" or something like that.