I'm not in a position to review this translation myself as my French isn't good enough, but readers should be aware of the long and very poor review given to it in the London Review of Books by Toril Moi (Vol 32. Pt 3, 11 February 2010). The reviewer says, "After taking a close look at the whole book, I found three fundamental and pervasive problems: a mishandling of key terms for gender and sexuality, an inconsistent use of tenses, and the mangling of syntax, sentence structure and punctuation."
And, "The book is marred by unidiomatic or unintelligible phrases and clueless syntax; by expressions such as `the forger being', `man's work equal', `the adulteress wife', and `leisure in château life'; and formulations such as `because since woman is certainly to a large extent man's invention', `a condition unique to France is that of the unmarried woman', `alone she does not succeed in separating herself in reality', `this uncoupling can occur in a maternal form.' The translation is blighted by the constant use of `false friends', words that sound the same but don't mean the same in the two languages."
Also, "The notes, bibliography and index are riddled with mistakes. Names are misrecognised and bibliographical references are botched."
If you're thinking if forking out £30, or even Amazon's reduced price, you might want to check out the whole review. It looks as if the earlier edition, which was only criticized for the cuts it amde and not for the quality of the translation, might be the one to stick with for a while.