I wholeheartedly agree with Edward Lilley's review here. This is an excellent box of early music, full of drama, spirituality and sheer beauty. There is a huge variety here from the mighty 40-part wall of sound on Utopia Triumphans and Brumel's stunning "Earthquake Mass" to the intimate loveliness of Agricola's two- three- and four-voice works on A Secret Labyrinth, with lots of wonderful stuff in between - much of it unavailable anywhere else. Paul van Nevel produces a fabulously warm sound from his very fine group of singers, with a particularly deep and full group of basses, and the recorded sound captures it beautifully.
For an excellent and very full account of each disc I strongly recommend that you read Mr Lilley's review and then snap this set up. It's a real gem.