According to Rams:
Good design is innovative.
Good design makes a product useful.
Good design is aesthetic.
Good design makes a product understandable.
Good design is unobtrusive.
Good design is honest.
Good design is long-lasting.
Good design is thorough down to the last detail.
Good design is environmentally friendly.
Good design is as little design as possible.
(Copyright Dieter Rams, amended March 2003 and October 2009)
I was so inspired by his words that I actually took more photos of his quotations than the actual products, so I'll leave you with my favourites: