This is a very brief post with another image. (I know some people don't find pictures convincing - in that case please see the YouTube video I linked to in my last post, where you can clearly hear the effects of the distortion.)
I have read people deny that the CD is clipped. Here are closeups of waveforms from the UK release of the CD (top) and the GH sample I was sent (bottom).
As you can see, the CD is clipped (the tops of the waveforms are "squared off" ) whereas the Guitar Hero version on the bottom is not. This is the cause of a least some if the distortion people are hearing.
However as I mentioned in a previous post, digital clipping alone isn't enough to make the album sound as distorted as it does. So yes, the album is clipped, but in my opinion the distortion probably results at least partially from an earlier stage in the process as well - presumably the mix.