This is one of at least three excellent albums from Black Sabbath with Tony Martin on vocals ("Eternal Idol" and "Tyr" are my other two favorites). "Cross Purposes" was the third Sabbath reunion in a row between 1990 and 1994.  First, Tony Iommi dismissed Martin in 1990 to reunite with Ronnie James Dio and release the "Dehumanizer" album.  Next, Dio left since Tony planned to do a one-off reunion with Ozzy for what was intended to be his last concert before retiring.  After that short-lived excursion with Ozzy, Iommi reunited with Martin to release "Cross Purposes," which many consider to be the best overall album with Martin singing.  My personal favorite is "Tyr," but it's hard to argue against "Cross Purposes."  The Tony's were both ON for this one.  Iommi riffs away like a man possessed, which is really no surprise when you look at "Tyr" and "Dehumanizer," the two preceding albums.  Tony went back to real heavy metal on "Tyr" after a few hard rock-oriented albums, and "Cross Purposes" continues the trend in grand fashion.  He offers a good mix of riffs that cover all the bases.  Some are slow and doom-drenched, some in the faster post-Ozzy style, some mellow and bluesy.  This is a strongly guitar-driven album with no filler.