I admire Rimbaud's writing, particularly Illuminations, but always find it obscure, like unreadable but beautiful hieroglyphs. Ross's book changes that, although not totally.
Although the focus is on the Paris Commune, Ross draws on many social contexts. Marx is present, unsurprisingly (my edition of this book is from Verso), but also Bakunin, and a solid if unsurprising stable of theorists (Lukacs, Deleuze, Todorov, Jameson). Some parts of the book are very unconvincing, and its central polemic (setting up Rimbaud as a political artist, in opposition to Mallarmé and aestheticism in general) just doesn't work for me. But it's a wealth of information and thought in a compact package. Ross establishes Rimbaud's historical situation without falling into speculation or mythography, even proving that several of his poems can only be understood through very specific, documented historical references.
Ross puts "hermetic" in scare-quotes when talking about Illuminations. I can't agree with that, I think it's a book built out of paradox, impossibility, and deliberate difficulty. But parts of it are clearer now than they were before, which is enough to make the book a success to me.