been listening to Mastodon: The Hunter.  early impressions are that it's good, although maybe not quite as good as the last couple.  i really like the sound of Mastodon, their records sound great, and i find i can actually listen to them since they started singing!  the early albums still sound great, but the vocal style was very wearing.  fine for a song or two, but over a whole album, it just irritated me.  the only problem i have with them is that a lot of their material does sound very similar, it can be hard to tell what song, or even album, you're listening to.  i do still listen though, because it's a sound i like a lot :)  
a friend asked me what they were like a couple of years ago, i said it was like a heavy rock band in the seventies got a letter describing what modern metal sounded like, and tried to recreate that without ever actually hearing any modern metal.  i like that description, even if you don't ;)
also, this morning, put on the Chickenfoot III album.  when did Keef Richards join the band?