Geoff Ward at The Dublin Review of Books:
So what was it that made Robinson Crusoe different from previous English fiction? First, Defoe was the first major writer in English literature who did not take a plot from mythology, history, legend or prior literature. The next was to be Samuel Richardson (1689-1761) whose immensely important novel Pamela(1740) it will be relevant to mention a little later. In the plots of these two writers we see the difference, for example, from Chaucer, Spenser, Shakespeare and Milton. Second, Defoe was the first to convey the reality of time, to portray a life in the bigger picture of a historical process, and in terms of day-to-day thoughts and activities. Although his timings are inconsistent, his narrative convinces us that the action is occurring at a particular time. Third, Defoe was the first to produce a whole narrative as if it took place in a physical environment to which a character was attached by means of vivid detail: the description of objects, for example, such as clothing and implements. Previously and traditionally, place was treated in a vague and generalised way, with only incidental physical description. Fourth, the use of figurative language, previously a prominent feature of romances, was noticeably reduced; it was much rarer in Defoe and Richardson than in any writer before.
more here.