Someone from the Steve Hoffman forums kindly shared a screenshot they took of the waveform for D-Mag's Guitar Hero mix. As you can see, it is dramatically different from the commercial release, which is almost totally brickwalled. "Brickwalled," of course, means that the waveform is so stretched out and compressed, that there is only a solid wall of green.
Needless to say, a green brick wall sounds hideous. It's absolutely unbelievable that the music industry has allowed the quality of their product to deteriorate so badly, all in the name of grabbing your attention for five seconds.
Death Magnetic's Guitar Hero mix is far, far better. I've seen other waveforms that are very similar to this. The results can now be seen as well as heard, and it's a completely different album. This is how a proper album mix should appear; not as a solid green slab, but as peaks and valleys, loud and quiet.