I initially read this book about a year ago, and it's a decent introduction to Marxist analysis of LGBT issues. It's short, accessible, and it has a phenomenal chapter rebutting the outsized influence of postmodernism in queer theory. However, it's not without a handful of glaring flaws. Wolf is a Trotskyist, meaning her view of 20th century Socialist States is that they weren't socialist at all. This cripples her historical analysis of LGBT rights in these States, and leads to absurd assertions and mistakes.
For example, the author condemns Mao's China as 'Stalinist' and not socialist, while praising The Black Panther Party, who was very much ideologically aligned with China, on the very next page. This is never properly addressed, and sticks out as wolf simply being selective of historical leftist movements, based on their favorability towards queer people. Furthermore, Wolf makes no mention of the Cuban organization CENESEX, which had been around for years in Cuba, advocating for LGBT rights. Seemingly, Wolf's Trotskyism causes her to gloss over this subject as per the reasoning that cuba is 'stalinist', and not 'really socialist'.
Ultimately, I'd recommend this book as an introduction, but take the history segments with a heavy grain of salt.