The system architecture determines how hard or easy it is to implement a given feature. Good architectures are those in which it is considered easy to create the features desired. In that the way to judge whether an architecture is good is whether the architecture is good for the purposes to which it is applied.
The definition of goodness has to be related to fitness for purpose. Is this glove good? I don't know. What are you doing with the glove? Are you throwing snowballs, cooking barbeques, or playing golf? There's a set of changes that are going to occur to a software system over time. Probably the utilitarian or most useful definition of goodness is the answer to this question: are the changes that will keep this system successful in this domain in this product line relatively easy? If they are, then it's probably a good architecture.