Since I'm only giving it 1 star, I'll try to justify it only with more objective aspects.
The sound quality is so poor that it looks like it is a mono made in the 50's, and not in 1972. Not only that, there are some serious issues specifically related to the recording process, especially the microphones. For instance, the first time the male chorus comes in, they enter so loudly that it feels like "hammering" the listener. And it is not because they sing that loud, it's because their microphones are clearly too close to them, if compared to the rest of the choir. Another instance is the "Credo", where the trumpets sound as if they were off-stage. And in the Crucifixus, while the orchestra plays piano, the choir, again, "hammers" the listener,- at least to me, they seem to also sing "piano", but it comes with an amplified sound, which I attribute to poor miking. Often, the timpani sound unduly muffed. And so on.
I value clarity very much, especially in a work with such a complex counterpoint. But in this CD, the distorted sound and bad recording quality seriously impair that. To make matters worse, Giulini chose to use only the organ as continuo, which can be problematic: as Minkowski noted, the harpsichord sometimes can greatly clarify the counterpoint. So, the use of the organ in a poorly recorded CD makes it complicated to properly find the voices.
The dynamics are also impaired by the recording. Since the mikes were so terribly employed, you don't get to listen to the actual dynamics Giulini used, which might have been good. However, as it is, the volume varies chaotically.
Finally the tempi are another hindrance. Giulini's pace for this recording is the slowest I know - it is even slower than Celibidache's live recording for EMI! There are moments, such as in the Credo and Et in Terra Pax, that it's so slow it gets boring. This is a 2 hour long mammoth, and even though this is one of my favorite works, this slow pacing makes it difficult to follow through.
The musicians commit some mistakes here and there: the choir makes clearly misses entrances in some fugues and the horn misses horribly in the introduction to the Quoniam. If this were a better recorded CD, I wouldn't mind that. But these mistakes come in a CD with bad sound, messy dynamics and too slow tempi, so they become "bigger".
Yes, there are some very beuatiful moments, such as the Sanctus and the arias sung by Janet Baker, but they account for a very small portion of the recording.
I was misled to buy this CD by the first reviewer (Kehler), who praised the sound quality so much I bought it without even listening to previews. Please don't make the mistake I did and don't buy this CD. The other performances on modern instruments I recommend are Celibidache's live version for EMI and, above all, my absolute favorite: Richter's studio recording for DG, which is one of my "desert island" choices! And, well, just get the whole box: Bach Sacred Masterpieces Johann Sebastian At the very least, do listen to the excerpts before buying the CD.