I know an album like the Black Album, that was met with such overwhelming success doesn't really need anyone standing up for it, but I do often find myself defending the albums merits to fans of Metallica that see this effort as a sell out that doesn't compare to their earlier works.
The intentionally more radio friendly hits like Enter Sandman and The Unforgiven which were aided by unforgettable music videos might be over played but they introduced heavy metal into the lives of tons of people who would have never given the genre a listen to before. Turning squares, girly girls, stoners, and jocks alike into metal heads is a feat that should be rewarded.
Plus, the entire album is full of hard hitting, if a little poppy, exciting songs. This is an essential album. And instead of comparing it to other releases, one should enjoy an album this great and legendary on it's own.
And, by the way, you should also see Some Kind of Monster.