I love this man's work. It seems incomprehensible for a human mind to have such vivid imaginations let alone put them into words the way he did. I originally found a lot of his stories off-putting due to their rather abrupt often ironic endings rather than Lovecraft's more tragic endings. I grew to appreciate them though. I've always been fascinated with ancient history, lost civilizations and continents etc since I was a kid so I love a lot of that stuff more than anything. Still my favorite tale of his is "The Nameless Offspring". Incredible atmosphere, sort of reminds me of a Blackwood tale except more visceral. Ghouls were one of his finest creations among many.
I recently bought the audio editions of the Nightshade books from audible.com and was pleasantly surprised. All the readings are great.
Here's a fantastic reading of "The Isle of The Torturers".