This was the biggest scam I read in recent memory.

It was introduced to me as some kind of proto-lovecraftian fever dream exploring the strange faraway lands of the titular King in Yellow, and it started out like Lovecraftian stories often do - upper society gentlemen of impeccable pedigree getting tangled up in the strange and occult. But after a few stories, of having hinted of the strangeness to come, the whole occult business was dropped, and the rest of the book was bog-standard Victorian romantic short stories.

I'd say you can get as much from the Wikipedia article and the poem, as you'd from getting the book.'

If you want the experience of exploring a weird and strange realm, I'd recommend 'The Dream-Quest of Unknown Kadath' from the man himself.