They're very light. Since they don't carry any weight you'd at least hope to learn something.
You'll get as much if not more from the free machine learning Georgia tech course with Tom Mitchell's book than the nanodegree.
As a follow up, I took Thruns robotic driving course and it suffers from being a purely software course. There are optional hardware projects but no imparted hardware instruction.
So I'd be especially leery of an automated driving nanodegree degree online.
