Williams’ wide-open yet engaging style was not that of a "free" player like Sunny Murray or Rashied Ali, but he was influenced by that era’s free jazz without leaving behind a powerful rhythmic stimulus - he improvised as much as any other player in the band. While the syntax of the earlier Quintet was for the most part intact - Davis and Shorter still played unison passages - Miles and company were reaching for an open-ended sound that took from the rock, soul/funk, avant/free jazz and electronic sounds of the day that did not pander to audiences nor leave them in the ozone - if one listens with closely there are always wisps, tinges and undertones of the Blues. As for the compositions, there’s a strong current of beautiful, haunting melancholia - NOT "gloom" - running through them.
Hey, if you know history, 1968 was indeed a tense, pivotal year in many ways for our nation and the world. And amid all this, Miles plays some of the sharpest, no-frills, laser-beam passionate trumpet of his career. Nobody knew it at the time, but this way the jazz counterpart to The Beatles' Revolver - the best of the present and shades of the past and future all in the same place.