Greeted with decidedly mixed reviews upon its original release, Exile on Main St.

has become generally regarded as the Rolling Stones' finest album.

Part of the reason why the record was initially greeted with hesitant reviews is that it takes a while to assimilate.

A sprawling, weary double album encompassing rock & roll, blues, soul, and country, Exile doesn't try anything new on the surface, but the substance is new.

Taking the bleakness that underpinned Let It Bleed and Sticky Fingers to an extreme, Exile is a weary record, and not just lyrically.

Jagger's vocals are buried in the mix, and the music is a series of dark, dense jams, with Keith Richards and Mick Taylor spinning off incredible riffs and solos.

And the songs continue the breakthroughs of their three previous albums.

No longer does their country sound forced or kitschy -- it's lived-in and complex, just like the group's forays into soul and gospel.

While the songs, including the masterpieces "Rocks Off," "Tumbling Dice," "Torn and Frayed," "Happy," "Let It Loose," and "Shine a Light," are all terrific, they blend together, with only certain lyrics and guitar lines emerging from the murk.

It's the kind of record that's gripping on the very first listen, but each subsequent listen reveals something new.

Few other albums, let alone double albums, have been so rich and masterful as Exile on Main St., and it stands not only as one of the Stones' best records, but sets a remarkably high standard for all of hard rock.