As to the novel itself, I am persuaded by Ken Hite:
Which is perhaps the most frightening thing, to me at any rate, about this piece. A (patchwork?) first draft, written in well under two months in 1927 and abandoned wrongly and foolishly by the author, is the second-greatest horror novel of all time. (Lovecraftian italics very much intentional.) The mind reels at how good a novel, and perhaps how many more years of Lovecraft’s life, he and we were cheated of by HPL’s “renunciation” of this work. It sat in pieces in his files or wherever for the next decade, while *four separate publishers* asked him if he had a novel they could see. Talk about lost and saved in a library.
…The radio play does it justice. It’s two hours long, but The Case of Charles Dexter Ward is worth it if you at all enjoy audio-only horror. This one may be my single favorite HPLHS Dark Adventure Radio Theater, and I rate this series highly. They really do get the atmosphere right in this particular production.