Rieu writes in continuous prose, keeping sentences long enough to carry the movement of the Greek without breaking into dramatic units. His register is plain and contemporary: in Book 21 he has Achilles say "Why make such a song about it?" and in Book 5 he calls Ares a "mad, double-dealing delinquent." Both phrases are conversational, almost blunt. Graves, despite his prose tag, opens the poem in rhyming verse couplets, with "Sing, Mountain Goddess, sing through me / That anger which most ruinously." That rhyme scheme pulls the opening away from Homer's direct declarative force and toward a lighter, song-like mode. In the Book 6 leaves passage, Graves adds a full stanza of rhymed quatrains where Rieu gives a single clean sentence. The tonal gap between the two translations is large. Rieu prioritises readability for a general audience, removing most of Homer's formal repetitions and epithets. In Book 9 he renders the mother's prophecy as reported speech, which moves the passage along but removes its quoted, oracular quality. Graves restores that quality by setting Thetis's words inside quotation marks as a separate verse speech, which matches the Greek more closely. Graves also retains more of the original's structural divisions between speakers. What Rieu gains is pace and accessibility; what he removes is some of the ceremony. Graves, by contrast, adds his own ceremony through rhyme, which the Greek does not have, and that addition changes the emotional register of nearly every passage he touches.
Anger — sing, goddess, the anger of Achilles son of Peleus, that accursed anger, which brought the Greeks endless sufferings and sent the mighty souls of many warriors to Hades, leaving their bodies as carrion for the dogs and a feast for the birds; and Zeus' purpose was fulfilled. It all began when Agamemnon lord of men and godlike Achilles quarrelled and parted.
Sing, Mountain Goddess, sing through me
That anger which most ruinously
Inflamed Achilles, Peleus' son,
And which, before the tale was done,
Had glutted Hell with champions—bold,
Stern spirits by the thousandfold;
Ravens and dogs their corpses ate
For thus did Zeus, who watched their fate,
See his resolve, first taken when
Proud Agamemnon, King of men,
An insult on Achilles cast,
Achieve accomplishment at last.