I'd disagree with that only because I (and everyone I've ever spoken to about it who has a CS degree) was forced to read it cover to cover (and for the record I hated it at first). The problem with saying it's a reference book is it isn't really written like a reference book. If you don't understand the context of what he's saying I don't see how it would be usable (especially considering the environment it describes is essentially hypothetical). So while I think it could be used as reference I think you have to have read it to use it in that fashion.