I assume you mean Astonishing Swordsmen and Sorcerers of Hyperborea, right? I got it last summer. Here are some pictures, if you are interested. It's pretty cool, though I haven't read every word and have only played it at Gary Con.
“A man may do both. For not we but those who come after will make the legends of our time. The green earth, say you? That is a mighty matter of legend, though you tread it under the light of day!” —J.R.R. Tolkien
Yeah, that's what I thought -- I don't need yet another rules system. But I like the idea of a purely swords & sorcery "weird fantasy" setting based largely on CAS, HPL, REH, etc. The pulp era. What a great idea! I ordered the box.
The Referee's Manual, which includes the Bestiary, Treasure and Gazetteer books, has plenty of setting material. Allthough the Players' Manual is more rules-oriented, I think you will still find it inspirational and anyone who knows AD&D should be able to convert the classes and spells pretty easily (if you don't simply import the AD&D set).
The point: you can definitely use this box set to run an AD&D game set in Hyperboria.