The second-most interesting thing about it is that wonderfully hyperbolic promotional copy! "...horsemen of the apocalypse..." "Filmed in Hollywood..."(!)
I particularly like the artwork on the cover. It appears to be one of the pre-production pieces created by Italian artist Niso Ramponi. (Somewhere around here I have more of Ramponi's Starcrash art. I'll have to dig it up soon.)
And just for the hell of it, here's one of the amazing Drew Struzan's pencil comps for a Starcrash (The Adventures of Stella Star) poster done for AIP before they dropped the picture.