It is such a good album for many reasons, one of these contributing reasons was that it was the first album after the massive controversy about St. Anger and the fact that with a lot of fans it didn't go down well, however I personally don't really mind St. Anger, because it was evident that Metallica were just experimenting with different sounds snd techniques to apply. I suppose that as many people say, they went back to their roots of relentless thrash metal for this album, it is a good thing but it is the music created by Metallica that people know and love, and with the songs like 'All Nightmare Long', 'The Day That Never Comes' and 'My Apocalypse' that just keep going, it shows that Metallica are really evolving, for the better