Quite frankly I really liked the art deco look, but it didn't quite click with me in vanilla. It's beautiful, crisp and clean, but I don't want beautiful, crisp and clean when its 3000BC, I want it to be like that when I have an actual advanced civilization on my hands. I would have preferred if the UI reskinned itself every couple of eras, much like the advisers seem to in G+K.
On a side note, the vanilla V menu screen was by no means the pretties of them all, a significant step back from the beauty that was 4 in fact, but the one in G+K is just absolutely dreadful! It looks like some badly designed mod, I hate it.