I thought I'd chime in a little.
I agree that James' singing was not the greatest in the 90's. I also agree that James is the greatest musician in the band and one of the greatest, if not THE greatest, metal song writers who has ever lived. And besides the drums, he also plays the piano/keyboards.
I do have to give Lars and Kirk a little love though. I really don't think Metallica would be Metallica without Lars. He has a very signature and easily recognizable style. Plus he is really good at helping James arrange the songs. And he's even written some really good riffs that have been used in some of their songs.
Kirk may not have the technicality that has become more common in metal lead guitarists, but I really like his solo style. It's almost like singing, but I'm not sure that's the right way to put it. And he's written some of Metallica's best riffs.
And... Load and Reload are awesome albums