Nowadays the Bee Gees seem like an acquired taste, but in the ’60s and ’70s millions of fans around the world acquired it. One of the trio’s distinctive voices, Robin Gibb, enjoyed a brief solo career, much of it collected and issued for the first time on this three-CD set. Disc one, his 1969 album Robin’s Reign, is excruciating. Disc two is better, piecing together Gibb’s lost 1970 magnum opus, his Smile, Sing Slowly Sisters, which in its best moments matches the fragile grandeur of the Bee Gees at their best.