Great design instantly draws the user’s attention to the intention of the interaction, blurring everything else – including the interface that’s enabling that interaction.
If your product or service draws attention to how beautiful or ugly the user interface is – well, it’s most likely not well designed. On the other hand, if your product or service draws attention to the intended interaction between the user & your brand, makes the user take action like its ‘obvious’ – you’ve most likely nailed the design.