There are, to a certain degree, some de facto elements such as a competent style, an original story and an attempt at entertainment throughout.
However, what really makes you sit up and think 'this was a good read' after a book?
for me, a good read is one that totally captures my attention both during and after the book for a considerable time. I must still be imitating the characters that i have fallen in love with in the book atleast a fortnight after i've finished it to consider it a good read.