First, let me make it clear that I didn't buy the whole set. The price and the volume is a bit intimidating, to say the least, and the sheer ubiquity of Harnoncourt recordings these days tends to breed a certain resistance in me. Therefore this review is based on the three discs I own (8, 9 and 10) - I'm withholding a star based on ignorance, not criticism. That said, I found the recordings delightful and more than once a pleasant surprise. The Masses can sound somewhat repetitive at times, but for me the real discovery was the many small and fragmentary pieces, which one doesn't come across often in other recordings. The Kyrie K.89 is a haunting vocal canon, so unlike a Mozart; the Miserere K.85, dark, powerful, with just a hint of Allegri; Kyrie K.322 and 323 little gems. The singing is clear and forceful. Contrary to the Amazon review above, I didn't find the baroque instrumentation to be a problem. I don't know if it's a good idea to buy the complete set (Amazon doesn't offer them individually, I think), but it's certainly a lot of CDs for the money -.- , and one thing I can say for sure is that there are bound to be similar discoveries for everyone.