Pushkin's 1837 "novel in verse" is exactly that. It has almost everything modern readers expect from a novel: big, distinctive characters, dramatic action, interiority, vivid scene-setting, a frame open enough to allow authorial comment (the narrator is also a "character"). And it's in fully rhymed and metrical stanzaic verse.
It was Charles Johnston, translator of the previous Penguin edition, who described "a sound-proof wall" separating Eugene Onegin and English-speakers, and regretted the absence from earlier translations of "the thrilling, compulsive grip of the novel; the tremendous gusto and swing and panache". Johnston's translation broke through the wall, at least partially. Stanley Mitchell's, too, succeeds to a remarkable extent. The narrative flows, the engaging voice of the narrator-raconteur emerges, all with painstaking fidelity to structure and sense. But is it really more important to replicate Pushkin's stanza than to convey the spirit of the work in a vigorous English idiom?
The 14-line Pushkin stanza is a dancingly light vehicle, but it was co-designed by the genius of Pushkin and the Russian language. Modern English is wordier, more rigid in syntax. Despite Mitchell's use of half-rhyme, the nuisances of over-writing and idiomatic fluctuation persist.
Mitchell notes that Johnston tended to "poeticise" Pushkin's language. But Mitchell, too, can be un-ironically poetic. Compare Stanza 1, Chapter 2: "The country place where Eugene suffered/ Was a delightful little spot;/ The innocent might there have offered/ Blessings to heaven for their lot." (Mitchell). "The place where Eugene loathed his leisure/ was an enchanting country nook:/ there any friend of harmless pleasure/ would bless the form his fortune took." (Johnston). Mitchell's "suffered" is an improvement on "loathed his leisure", but both stanzas miss the crisp simplicity of the original.
Mitchell claims "a contemporary idiom that avoids the antiquarian or the modern/post-modern". But what is contemporary in an idiom allowing grammatical inversions and such words as morn, wondrous, beheld, thither? There is great pleasure to be had from reading this version, but it is probably fair to say that Mitchell's English has a more old-fashioned flavour than Pushkin's Russian.