With all due respect, I don't think we should judge the Queen by other people action other than her own. I wouldn't compare her to Gorbachev, Clinton, any of the Bushes, Obama, or Beatrix of the Netherlands. She is her own woman.
From what I have read from her, while she is a woman of great wealth, she has never flaunted it. Nor do we know everything about the Queen. Contrast to the rest of her family, whose private life has been splashed ALL over the world. We don't know if the Queen gives Christmas bonuses to her employees or how much she donates.
In the US, politicans are required to release their tax returns. So every year we know if they are or not giving to charity. From what i understand, the Queen doesn't have to publicize this information, is that correct? So techinically she should could be as stingy as a kid with a new toy or a very giving woman? We just don't know.