Rocking the Classics
The book Rocking the Classics by Ed Macan has this to say about Gentle Giant:
"Gentle Giant added elements of cool jazz and renaissance music to the symphonic/folk framework, creating a dauntingly complex approach characterized by spasmodic rhythms, dense textures, and an extraordinarily varied instrumentation. Their almost manneristic progressive rock can be heard to best effect on OCTOPUS (1973) and the excellent FREE HAND (1975)."
"Suffice it to say that no one is likely to confuse the savage energy of King Crimson and Van der Graaf Generator in their mid-1970's incarnations with the disinterested density of Gentle Giant..."
"Progressive rock was able to solve yet another challenge posed by the psychedelic jam - how to create a sense of direction - by drawing on 19th-century symphonic music's fondness for building up tension until a shattering climax is reached, upbruptly tapering off, and then starting the whole process anew.... An effective extension of this technique involves marking off a climax by using electronic instruments to give a heavy rock treatment to a theme that had initially been stated quietly in an acoustic setting (notice once again the feminine/masculine dynamic at work again). ELP's "Trilogy," UK's "30 Years," Gentle Giant's "His Last Voyage"..."