I thought it reflected incredibly badly on the character of Buffy, especially with how she completely blew away Spike's right to be upset about it. Added to smiling over his still warm ash, the basking and the indignation that he had the temerity to be upset made me want never to see her nasty little face again, and to want something better for Spike. Someone capable of growing up, not someone who signally failed to do so over 7 years of a growing up tale.