Death Note is universally appealing. It has some kind of magic that digs in and holds fast to the heart of anyone watching. It is obviously well-written; the plot is solid, the suspense sublime, and the characters? Best Characters in Any Work of Fiction Anywhere Ever.
But even all these elements combined don't account for Death Note's magnitude of charm. Its whole is greater than the sum of its parts, great as that sum already was.
For a friend who just couldn't get into anime, I recommended Death Note. It's impossible not to get sucked in by the masterful writing, airtight characterization, and that indefinable something extra: that magic spell Death Note casts on its viewers.