Old and New
One thing that Robert Graves is really well-known for is the way that he continues to use poetic forms and devices that many other poets of his time would have considered outdated or even tacky. The heroic couplet, for example, was something that people would have associated with the age of Alexander Pope. But Graves respected and revered the history of classical poetry, and he was more than willing to take people's criticism if it meant paying his respect to this history.
But Graves isn't exactly writing poetry for dead audiences. He also has subtle little way of taking classical forms and updating them for the modern age. For example, he makes sure to never rhyme the opening two lines of any of his stanzas. It's almost as if he starts each stanza by reassuring us that he's a modern poet. But as soon as he has our attention, he plunges us back into a rhyming couplet. It's like he's saying "gotcha!" the moment we start to relax. Check out "A Boy in Church" or "A Renascence" for more "gotcha!" moments.