I guess it's just because of the neat cover, I don't think any of the stories are particularly rare (The Colour out of Space obviously isn't). The selection is pretty good, though.
Edgar Allan Poe, "MS. Found in a Bottle"
Bram Stoker, "The Squaw"
Ambrose Bierce, "Moxon's Master"
Ambrose Bierce, "The Damned Thing"
Ambrose Bierce, "An Inhabitant of Carcosa"
R. W. Chambers, "The Repairer of Reputations"
M. P. Shiel, "The House of Sounds"
Arthur Machen, "The White People"
Algernon Blackwood, "The Willows"
Henry James, "The Jolly Corner"
Walter de la Mare, "Seaton's Aunt"
H. P. Lovecraft, "The Colour Out of Space"
I'm familiar with Pierce's "Damned Thing" and "Carcosa" and Chamber's King in Yellow stuff. Most of the rest sounds familiar, but I haven't read it.