Sri Aurobindo notes about the style of Vyasa, the following:
"It is indeed, I believe, the general impression of many "educated" young Indians that the Mahabharata is a mass of old wives' stories without a spark of poetry or imagination. But to those who have bathed even a little in the fountain-heads of poetry & can bear the keenness & purity of those mountain sources, the naked & unadorned poetry of Vyasa ...To read him is to bathe in a chill fountain in the heats of summer...infusing strength, courage and endurance.
There are certain things which have this power inborn & are accordingly valued by those who have felt deeply its properties, such are the air of the mountains or the struggle to a capable mind with hardship and difficulty; the Vedantaphilosophy, the ideal of the निष्काम धर्म, the poetry of Vyasa, three closely related entities, are intellectual forces that exercise a similar effect & attraction.
The style of this powerful writer is perhaps the one example in literature of strength in its purity; a strength undefaced by violence & excess yet not weakened by flagging and negligence. It is even less propped or helped out by artifices and aids than any other poetical style.
Vyasa takes little trouble with similes, metaphors, rhetorical turns, the usual paraphernalia of poetry; nor when he uses them, is he at pains to select such as shall be new & curiously beautiful; they are there to define more clearly what he has in mind, and he makes just enough of them for that purpose, never striving to convert them into a separate grace or a decorative element. They have force & beauty in their context but cannot be turned into elegant excerpts; in themselves they are in fact little or nothing.
When Bhema is spoken of as breathing hard like a weakling borne down by a load too heavy for him, there is nothing in the simile itself. It derives its force from its aptness to the heavy burden of unaccomplished revenge which the fierce spirit of the strong man was condemned to bear.
We may say the same of his epithets, that great preoccupation of romantic artists; they are such as are most natural, crisp & firm, best suited to the plain idea & only unusual when the business in hand requires an unusual thought, but never recherché or existing for their own beauty. Thus when he is describing the greatness of Krishna and hinting his claims to be considered as identical with the Godhead, he gives him the one epithet अप्रमेयः immeasurable, which is strong and unusual enough to rise to the thought, but not to be a piece of literary decoration or a violence of expression. In brief, he religiously avoids overstress; his audacities of phrase are few, and they have a grace of restraint in their boldness."
Sri Aurobindo - Notes on the Mahabharata [re-formatted for easier reading online]