Upon being introduced, the very confused Mr. Dupin (Edgar Allan Poe) begins to create his own opinions of the people around him.
Among a big group of very solid admirers, the last to be introduced by Mrs. Whitman was Mr. McFarlane, whose credentials included the recognition of being a local poet from Providence. Mr. McFarlane did not cause a good impression in Dupin, basically due to his extremely cheerful disposition, which caused Dupin to dislike him. Also, McFarlane was a sycophant whose words for Dupin/Poe were quite splendid:
But I am not so fortunate in glory or genius as the famous Mr. Poe.
This is where the narrator says that, although McFarlane was "bald and cheerful", Dupin still "took him for a devil". In fact, Dupin is, in general not happy with just about anybody he has met.