I came across the short story, The Great God Pan as I was preparing a few of my own horror shorts for submission to publishers. I'd also seen it recommended in an article by Steven King. Thus, I picked up a copy to give it a read. I was not disappointed.
The story was disjoint, following several different characters in a few different places and jumping time. I found the tell of the story similar to Bram Stoker's Dracula, drawing from several sources to compile one story line, though it that story isn't given to us readers sequentially. I enjoyed the book, and as is needed for such a disjoint presentation, all the parts came together in the end to a satisfying conclusion. The characters were interesting, though I'll note the characters we follow were not particularly diverse.
My only issue with the novel would be the clarity of characters. In fact, I was thoroughly confused by the last chapter, as to what character we had returned too, and I couldn't grasp the story climax without knowing. I read it twice and ended up having to go look up online which character was narrating the last chapter. What I found was the last chapter had three distinct sections, each with its own narrator, each a return to a previous character. With that knowledge, It all made since.
I was satisfied with the end, and the copy I got of the story was many times removed from the story's original publication. I suspect, the story has aged to public domain, and I believe the publisher took some short cuts to get the story on fewer pages. Thus, I don't know if a better-formatted edition might not have left me confused on that last chapter. As a result, I don't feel right to rate the story lower because of this narrator confusion issue. You get the benefit of the doubt Mr. Machen, five stars.