When the narrator meets Usher, what startles him most about Usher's appearance and behavior?

From the text:

We sat down; and for some moments, while he spoke not, I gazed upon him with a feeling half of pity, half of awe. Surely, man had never before so terribly altered, in so brief a period, as had Roderick Usher! It was with difficulty that I could bring myself to admit the identity of the wan being before me with the companion of my early boyhood. Yet the character of his face had been at all times remarkable. A cadaverousness of complexion; an eye large, liquid, and luminous beyond comparison; lips somewhat thin and very pallid, but of a surpassingly beautiful curve; a nose of a delicate Hebrew model, but with a breadth of nostril unusual in similar formations; a finely moulded chin, speaking, in its want of prominence, of a want of moral energy; hair of a more than web-like softness and tenuity; these features, with an inordinate expansion above the regions of the temple, made up altogether a countenance not easily to be forgotten.