The famous Arabist H A R Gibb was open upon about the style of the Qur’an. In his words: …
the Meccans still demanded of him a miracle, and with remarkable boldness and self confidence Mohammad appealed as a supreme confirmation of his mission to the Koran itself. Like all Arabs they were the connoisseurs of language and rhetoric. Well, then if the Koran were his own composition other men could rival it. Let them produce ten verses like it. If they could not (and it is obvious that they could not), then let them accept the Koran as an outstanding evident miracle.
And in some other place, talking about the Prophet(P) and the Qur’an, he states:
Though, to be sure, the question of the literary merit is one not to be judged on a priori grounds but in relation to the genius of Arabic language; and no man in fifteen hundred years has ever played on that deep-toned instrument with such power, such boldness, and such range of emotional effect as Mohammad did.
As a literary monument the Koran thus stands by itself, a production unique to the Arabic literature, having neither forerunners nor successors in its own idiom. Muslims of all ages are united in proclaiming the inimitability not only of its contents but also of its style. …. and in forcing the High Arabic idiom into the expression of new ranges of thought the Koran develops a bold and strikingly effective rhetorical prose in which all the resources of syntactical modulation are exploited with great freedom and originality.