Metallica is a great band. That's not even up for debate. Their albums are solid (Load and Reload included) and every cover they've ever done I honestly think has been better than the originals. Conversely, I can't think any bands that have done a cover of a Metallica song and done it better . . . with one exception . . .
Check out Godsmack's cover of Nothing Else Matters and tell me what you think