As I've given Metallica's Death Magnetic a few spins (and plan to do quite a few more in the near future), I must remind myself to judge an album itself, not judge an album based on crappy-sounding video and audio clips that appear online a year before the album comes out.
When a band makes an album, they're trying to make a definitive version of a collection of songs. Of course things are going to sound different live, but bands try to make some sort of studio documentation to an era in the band's life. Even if Metallica did a note-for-note re-recording of Master of Puppets now, it wouldn't be the same as the original recording. Not even the best available technology can recreate and capture a band's past in the present. So the band worked hard on creating something they can be proud of and represents who they are now. And it takes years for them to create something, but I don't mind. As a fan, I'd rather have nine distinct and solid Metallica albums over a 27-year career than nineteen soundalike albums and one definite record.
My point is that when a couple of new, in-the-works songs were performed live last year and earlier this year (and were quickly found on YouTube), I wasn't expecting much. The songs sounded kind of rough mainly because of the sound quality. Ditto when the band debuted the studio version of "The Day That Never Comes" online. Rather than posting a high quality version of the song, instead was a very low quality version that sounded like a demo being played through your neighbor's wall. I really wanted to make a decision on whether or not I would devote a lot of time to Death Magnetic until I heard it on CD.
Now that I have made my decision, I think about another instance where people I knew judged an album many months before it came out based solely on rather poor-sounding live clips: Radiohead's Kid A. A number of its songs were performed live, but if I remember correctly, a number of the songs sounded much different live than their studio renditions. So I ask why people say an album is great (or not great) even when the album isn't even done?
I guess my bigger point is this: judge an album based on the album itself. Judge a live version of a song on what you hear in concert or on MP3 or YouTube. Even though the band is the same band that recorded these songs, many factors make the distance between the band in the studio and the band onstage very, very wide.