The corrected text from a recently discovered manuscript is the highlight. This is the tale as Lovecraft envisioned it. Anyone familiar with "The Annotated H.P. Lovecraft" will appreciate S.T. Joshi's meticulous notes and annotations. He adds another layer of insight to these familiar stories.
My favorite feature, however, is the restoration of the pulp cover from Astounding Stories 6-36 where the story first appeared. It is nice to see the pulp roots of H.P. Lovecraft being honored.
If you liked 'At The Mountains of Madness' you should enjoy this book AND already know what the answers are!