There are a few pieces on the topic of what makes a design good that jumped out at me recently. First, I like this approach from Uday Gajendar in What is good design?:

So what is “good design”? It’s an attitude of design-driven excellence (from strategy to delivery), a process of iteration and creativity, a mentality of enabling humanistic achievement for people, and a value system grounded in excellence of craft with a magnanimous bent towards what’s best for customers: appropriate, empowering, delightful.

Jon Bell talks about “Of Course” Design:

When people try to design magical interfaces, they’re often aspiring for the “wow” moment, but that’s the wrong focus. Designers should instead be focusing on “of course” moments, as in “of course it works like that.” Most product design should be so obvious it elicits no response.

Finally, Randy Hunt implores designers to Stop Trying To Be So Damned Clever:

During the design process, you can easily want to surprise and delight the user. So you create a design element — an interaction pattern, a naming scheme, a symbol, and so on — that is fresh and extremely inventive. However, the cleverness of your creation obscures the intent of the product. And the cleverness of that first impression doesn’t hold up over time — and I don’t mean over years; I mean over only the first few moments of use. After that first rush of newness, if the intended value of the product is not clear, or the functional intent isn’t obvious, the novel idea means nothing.

All three posts are worth reading in detail for their different points of view that point to similar definitions of good design.