Describing and conveying the flavor of sake has always been problematic. How does one explain a gustatory experience in words alone? It certainly isn't easy. And, as sake flavor profiles become more complex and subtle, it is bound to become even more difficult.
Long ago, before the days of amazing new yeast strains, modern technology and market-enlarging infrastructures, sake was much simpler. Much if not all sake was divided into two camps: amakuchi or karakuchi (sweet or dry). Today as well, we can quickly say a sake is sweet or dry, relative to some standard we hold, arbitrary as it might be. But there is so much more happening in a glass of sake to talk about.
One other system used to describe sake flavor, and in particular the balance of flavors, is the go-mi (five flavors) system. The five flavors are karami (dryness), amami (sweetness), sanmi (acidity), nigami (bitterness) and shibumi (tough to translate, but try astringency or tartness). This is originally from Chinese Taoism, which says consuming these five flavors, will keep you healthy. (There are actually other manifestations of the go-mi, but this one is most common.)