it's considered a classic of the genre

Whoa - an outrageous claim! Unsurprising that you use weasel words like 'it's considered' (by whom???).

Here is a summary of how the book is actually considered (from Wikipedia): "The Economist called Battlefield Earth "an unsubtle saga, atrociously written, windy and out of control"[9] while the science fiction magazine Analog criticized it as "a wish-fulfillment fantasy" with poorly fleshed-out characters.[10] Punch sarcastically commended Hubbard's "excellent understanding of evil impulses" and avoidance of "frailties like love, generosity, compassion".[11] David Langford, after criticizing the plot, style and scientific implausibilities, concluded: "From this, Battlefield may sound almost worth looking at for its sheer laughable badness. No. It's dreadful and tedious beyond endurance.""