I haven't rated Metallica for a long time, and I don't even consider some of their earlier work the "classics" they were hailed as, even their best albums are still fairly formulaic, if listenable, metal, but nothing amazing. I have to admit, though, I'm interested about this one. Rick Rubin as a producer could, hopefully, breath some new life in to them, and hopefully Rob Trujillo will be involved in the writing process in a big way, seeing as he's my favourite bassist not named Les Claypool or Jaco Pastorius, but that seems unlikely.
If Lars gets his act together as well, this could turn out amazing. I won't hold my breath, but I'm intrigued as to how it will turn out.