How was Louisa, a Poetical Novel, in Four Epistles different from a typical novel?

Louisa, a Poetical Novel, in Four Epistles (1784) differed from a typical epistolary novel primarily through its form: it was written entirely in verse rather than prose.1

While it utilized the epistolary structure common to the genre, its composition as a series of four poetic epistles was considered both innovative and risky at the time. The work was deeply influenced by the era's cult of sensibility, a thematic focus that permeated its narrative structure.1