It sticks with you.
Ignoring those who lack the attention span for subtlety, this film is very close to a master piece. Kinski's character is amazing in his simultaneous existence as menacing and completely and utterly pathetic at the same time.
The shots, the atmosphere, the creepy despair laden music...
The subtle psychology.
The scene in the center of town where people know they have the plague and are trying to enjoy every last minute, rats everywhere, with haunting choral music in the background...
It's extremely slow and you have to have patience, but Herzog's genius is easy to feel.