Fucking great album, my first and favorite Metallica album.
I love the concept, its a lot deeper than Kill Em All 'bang your head' type lyrics. The guitar is nice and crunchy, drums are punchy, bass is in the background where it should be left. I've no complaints, there's not one weak song, perhaps One is a little catchy and grows tiresome after a while, but its a necessary break on an album like this. Too many bands these days expect you to sit down and listen to full on fast and heavy music without a break in speed. Metallica knew how to balance their albums out. I think its their most progressive album, it takes the longest to appreciate, but every time you listen to it you enjoy it more. But like all other Metallica albums, the road is more enjoyable than the destination.