As to what road they went during the 90's to present day does not reflect anything at all like "Kill 'Em All". It was blatantly obvious with the release of "The Black Album" they simply abdicated their thrash metal roots and completely sold out. But focusing on this album, the rhythms and leads are innovative, Hammett simply shredding on lead and Cliff Burton (RIP) puts out his talent on bass with "Anesthesia - Pulling Teeth". You could actually hear the bass guitar not only on that track, but all of them entirely. Fuzzy bass tone.
There really aren't many thrash acts during the 80's that were more innovative in songwriting quality than Metallica. Although I do consider Slayer, Exodus, Testament and Anthrax were also some damn good thrash bands as well. But Metallica reigned superior over these other bands. Musically "Kill 'Em All" has guitar riffs that are simply unique, awesome, distorted as all hell and memorable tracks from beginning till the end of the album.
I would consider this album to be one of my most played out records that I've heard, but I still am not sick of these songs. It's a shame that a band that displayed so much potential which is evident on this release all the way up till "...And Justice for All". I think that if Cliff Burton was still around they probably wouldn't have taken their thrash roots away and become a total waste musically. Maybe some would argue this but I believe that he would've at least kept them within their thrash/speed metal origin.
The lyrical aspect of this release has nothing really to do with Satanism, just filled however with hatred towards humanity without any compromise in that respect. Hetfield's vocals go well with the music especially the high-end screams. I don't consider this release their best of the 80's I'd say "Ride the Lightning", "Master of Puppets" and "...And Justice for All" were their absolute best releases. However, this was a beginning for the band and showed their awesome potential at such a young age.
Metallica used to scoff at the idea of making videos. However, after "One" came out they began to make more music videos to make more money obviously. That's why I'm reiterating the point that if Cliff was still around they wouldn't have become "Metallisux" as coined by most old fans of the group. But "Kill 'Em All" is pretty much everything good that I look for in a thrash/speed metal release. If you don't have it already in your archives then I urge you to pick it up ASAP!!!