The Sappho Companion is a perfect book for any translator, critic, or poet. It is a historical overview of what people have been saying about Sappho since her own lifetime. I learned quite a lot about literary fads and myths.
For example, in her own lifetime, critical emphasis was sometimes on the greatness of her poetry, sometimes on her status as a poet relative to other women poets. After her death, for hundreds of years Sappho was written into plays, and the myth of "Sappho's leap" arose, the idea that for unrequited love of Phaon, she lept off the Leucadian cliffs into the sea. Reynolds and other scholars claim that Phaon was actually another name for Adonis, and Sappho wasn't necessarily writing of her personal love for a guy named Phaon, and there is no evidence for a suicidal leap. That came later, in Greek comedies and tragedies about her life.
Reynolds also delves into concepts of Sappho as teacher, as lesbian, as bi, as a poet overcome by passion, as "chaste", as cautionary tale about the dangers of love and writing, as representative of "the New Woman"; until it becomes clear that at different times and in different countries, what anyone at all means by referring to "Sappho" is amazingly variable. Each chapter covers references to Sappho during a particular place and time, thick with examples. At the end of each chapter there are long excerpts from poems, novels, and plays. I loved this format, as it allowed for deeper understanding of the texts under discussion without the tedium of footnotes. (And as a side note: here's a cool link to a page with 26 different translations of Sappho's jealousy/passion poem, the one Barnard translates as "He is more than a hero/he's a god in my eyes...")
Why is this important for translators? It is a beautiful example of how translation of Sappho's work changed over time. But not only that. In my own work, for example, translating 19th and early 20th century women poets, it's hugely important for me to realize that their references to Sappho or to elements of the Sappho mythos are different from my personal concept of Sappho. In other words, I came to Sappho from a combination perspective of the Mary Barnard translations and 70s lesbian feminist interpretations! And that's not the same Sappho that Mercedes Matamoros is writing about in her 1902 book El último amor de Safo. Matamoros was a Cuban poet and a translator of Byron, Chenier, Goethe, Schiller, and others; she was part of a literary circle that included many women writers such as Aurelia Castillo, Nieves Xenes and her sisters, Luisa Pérez de Zambrana, and Gertrudis Gó de Avellaneda. What Margaret Reynolds' book did for me is to underscore the importance of figuring out historical context from the examples I can find, and the danger of making assumptions! I'm keeping that firmly in mind as I translate Matamoros's Sappho poem cycle. I also look to other poem-cycles on Sappho and Phaon, like Mary Robinson's from 1796. I can't prove that Matamoros read it, but it's good background anyway as it seems likely she would have read something similar to pick up her Sappho mythos.