Lovecraft’s writing is, well, I’d have to call it fevered: articulate, highly vocabulous, vivid, and yet pretty far off the perpendicular. You can count on the appearance of baroque adjectives (“a testudinous chuckle”; “a kind of pandaemonic cachinnation which filled the countryside”), certain recurring descriptors (such as “blasphemous”), highly complex sentences, lurid imagery, and beautiful, bewildering, alluring, and seemingly delirious dreamscapes. He had extensive knowledge of ancient cultures and literature, which he incorporated in a natural fluency that his less erudite imitators could never achieve.
He also had a passionate fondness for the old New England towns and villages, which always seem to cloak some secret (preferably blasphemous) presence and which he lovingly referred to as “ancient” even when they were a scant three centuries old.
His rendering of local dialects, however, is the one utterly unpalatable feature of his stories. It’s very hard to do well, and many an author has floundered with it; although Sir Walter Scott, for one, and George Eliot, for another, pulled it off somewhat bearably. Lovecraft should have gone with the principle of including just a sprinkling of stylized speech to give the flavor of accent and dialect while keeping the preponderance of it in plainspoken English; but he didn’t. Luckily there is not a great deal of rustic speech in his stories.
In his essay on writing weird fiction, he said: “Inconceivable events and conditions have a special handicap to overcome, and this can be accomplished only through the maintenance of a careful realism in every phase of the story except that touching on the one given marvel.” That sharp-edged contrast is a hallmark of his stories.
In 1975 I read a fascinating bioigraphy of Lovecraft by L. Sprague De Camp that set a context for the stories in Lovecraft’s own anomalous life history. I often wonder what it can be like to know someone as extraordinary as that; but then I think—maybe no one can, except by knowing his work.