I have a bit of early music (des Pres, Tallis, some madrigals and the like) and a lot more baroque. What I really like about the Vespers is that they demonstrate the evolution from early to baroque quite clearly. You get both the sense of chant - and maybe madrigal forms with some of the parts for single voices - as well as the seeds of baroque style, especially in the full choral sections. Where this differs most clearly from early music is the orchestra itself to support and augment the voices.
However, that is just a description of what it resembles - the thing itself is amazing. Monteverdi used full choirs, split choirs and many parts for individual voice and small groups to create a remarkable audio tapestry. My wife thinks I am a little nuts right now but I urge you to sit down between the speakers, put this on and crank it up a little - especially in the Dixit Dominus. It is astonishing. Pearlman, the orchestra and choir of Boston Baroque have done a fabulous job.
