DNB describes Rhydderch as a "competent if not imaginative poet, best known for carols and ballads." His greatest significance is as a patriotic Welsh printer and bookseller, offering almanacs, a dictionary and grammar, devotional and moral works, and chapbooks and ballads for an increasingly literate Welsh-language audience. His almanacs promoted the idea of an eisteddfod. Interest in Welsh cultural history and poetic institutions is here paired with a business interest in bringing modern print culture to Wales.