As AC / DC fan I had pre-ordered the MP3 album, because it belongs to my collection.
The album rock or Bust is not bad, but it is not a deal breaker.
Perhaps it has also been too spoiled with the good old songs of AC / DC and you expect more and more and more ... This is of course for as a band after 15 albums (16 albums in Australia) also not so simple its fans new to continually inspire.
My favorite Hammer albums where the songs really come off (o ;, are still "Back in Black and Highway to Hell".