Sexy. The trend has been that gold jewellery is commonly referred to as 'tacky', 'gaudy', 'cheesy' 'bling' etc so people throw those terms at anything called the colour 'gold'.
Aesthetically though, the gold, or rather, champagne, iPhones are the most pleasing as the subtly of the shade matches the refinement of the design. If you consider something so refined, in a subtle shade, 'gaudy' then your perception is bizarrely skewed beyond the normal boundaries of preference of taste, and it's more likely that you're overreacting rather than genuinely expressing an opinion on the aesthetic of what you're looking at. Apple do great hardware design, and they're very conservative with the colours and this shade is definitely conservative.
That mock up is a bit nicer than the actual iP6 though, as the real 6 has some white bands that ruin it somewhat.