Laci Green is a self-described sex education activist. She’s pro-BDSM and pro-erotica, but in this short YouTube video she gives her reasons why she finds the books of 50 Shades problematic in their portrayal of relationships and BDSM. In a nutshell, she says 50 Shades might be an entry point for some people to explore BDSM, but shouldn’t be used as a guide. Content note: some colourful language.
EDITED TO ADD (July 2017): The Establishment reporting recently Laci has seemed to move to defend anti-feminists. If haven’t fully researched this for myself, but if the article is true, then please be aware that whereas I think this video is on point, I do not agree with these other views!