Wikipedia got it right. Starts out as a long and harrowing sea tale, and then turns into a strange fantasy adventure. I was a little put off initially when the fantasy element was introduced, but over all enjoyed the book.
I can't believe I never read Lovecraft before! Cool, creepy and intriguing. Even though some of the story elements were a little predictable, I still wanted to read through to the end.
Another good one from Lovecraft. Interesteing descriptions of the wierd creatures (see the cover!). Cool concept, overall enjoyable.