Although people usually compare it to the ES 335 ("like a 335, but three inches thick"), it is actually more like a double cutaway version of an ES 175, in that it is a true hollow body, without the wooden block supporting the bridge (as in the 335 and other "semi-hollow body" guitars). The sound is indistinguishable from an ES-175, and it plays like one other than the double cutaway (and better access to upper frets). Gibson made use of this access by extending the fretboard to 22 frets, rather than the 19 frets on most ES 175s.
I bought mine in Denver, in 1971...my first jazz guitar, and the only guitar from that portion of my life I didn't eventually sell or trade. I never will. Someday, when I am gone, that guitar will go to one of my guitar-playing buddies.
It's a wonderful and unique guitar, and its rarity adds to its appeal.