I just listened to Slipknot's All Hope is Gone and Metallica's Death Magnetic.
Those two albums rock big time!
Slipknot's altough not as brutal as the previous ones is a logic evolution to the band's music.
Metallica on the other hand has done a complete 180o and reverted to their glory days of Master of Pupets and Ride the Lightning sound wise. The songs are not as epic as the two masterpieces's ones, but gone is the muffled sound of the idiot known as Bob Rock. that's a great relief.