Complex sentence: How much of the music is actually Monteverdi's, and how much the product of others, is a matter of dispute, though the work is generally accepted as part of the Monteverdi operatic canon, his last and perhaps his greatest work.
Split into simpler sentences: How much of the music is actually Monteverdi's, and how much the product of others, is a matter of dispute. Despite these uncertainties, the work is generally accepted as part of the Monteverdi operatic canon, his last and perhaps his greatest work.