In CQ25, たにかわ てつぞ argues that 茶の湯 is composed of 4 aspects, which are all interdependent and each practitioners style will give different importance to those aspects.
artistic element
social activity
formal decorum
ascetic training
Manners are important, but more important is thoughfulness:
利休 praised ちくあん, when he made tea but was trembling for excitement and knocked over 茶筅 and 茶杓.
つじ げんさい was じょうおう first student, and even though he knew it all, people said his 茶の湯 was lacking.