They had the right combination of stage energy, good song writing, good playing, and good musical ideas to really equal an ass kicking band. Many thought they were the best show in the business. I must say that I only got to see them once before the Horrible Downfall. I don't know what happened. The black album was alright.
Most people knock it, but overall it's a good disc.
But it's not what people expected from Metallica. It's a much simpler sound. It got by on raw energy of basic but powerful riffs. Thats not what people liked about Metallica though. They came a long way from Kill Em All, when everything was the same minor pentatonic solo on top of some tremelo picked rhythm.