She was a woman who was certainly self indulgent, but then she has never been given much of a life, as her husband died shortly after their marriage, and she was then exiled to his domain of Kourland. She wasn't well off, the place was boring, and she was rarely allowed to visit her family back in Russia. She was also not allowed to make another dynastic marriage. She did have lovers there, but not much else. All in all, she wasn't a great Empress, or even very good, but she was trying to make up for her early life.
I don't think she was a beauty either. She was also very German influenced for a woman who had only Russian blood; which could have come from her many years in Kourland which was very Germanic.