James Hetfield, lead singer, rhythm guitarist, and main writer of Metallica, is truly one of the more underrated rock/metal guitarists of our current time.
That is quite a profound statement, but I've yet to see anyone with the combination of technical prowess, muscular independence, pride, and downright rock and roll know how besides him. He has the ability to play technically difficult riff, harmony, and solo lines while keeping a straight posture and singing flawlessly, without fail.
People don't give him enough credit for what he's personally done for what was the heavy metal scene. When most think of Metallica, their brains quickly turn to the blindingly fast leads of Kirk Hammett or the good percussion work of Lars Ulrich. Someone had to write these songs, to architect these master compositions of monolithic metal.
Do yourself a favor, dust off your copy of Master Of Puppets, ...And Justice For All, or Ride The Lightning and give it a good listen, lean your head back, and ride the flow. You'll be happy you did.
-herbman, Metallica fan.
update - James is currently in rehab for alcoholism. Best wishes to him.
updated update - James is out of rehab, successfully, and is working with the band on a new album. Congratulations!