Based solely on pictures (obviously) the back is the worst looking back of an iPhone to date (IMO). Does that translate to hideous? I don't know. I think the current iPhone back is stunning, so in comparison, the new phone back is ugly, at least.
It isn't jewellery, but I can understand why many people treat it as such.
http://en.wikipedia.org/wiki/Form_follows_function
http://www.gizmodo.com.au/2012/08/why-a-two-tone-unibody-iphone-makes-perfect-sense/