Look what I just found...
I like my old versions of the book better, even if my paperback is falling apart. I also like reading Georgiana Duchess of Devonshire not The Duchess, but I'm a very particular person. The previous prints might be become more difficult to find now, as usually happens when the movie version comes out. However these seem to be cheap.
I guess this also means that the poster is official. For my blatant rant of hatred for the poster see this post, although you might want to spare yourself. I would suggest buying the much prettier versions of Amanda Foreman's book before it is too late!
US Version with the Reynolds Cover
UK Version with the Gainsborough Cover