The Yo Yo Ma perspective on Piazolla is a credible introduction to the profoundly evocative melodies of the master bandoneon player and composer but the nature of the context lacks means that these performances in some way lack the fire of the original. The difference is simply that which exists between a cello and bandoneon. The smoothness of Ma's cello is a little, and only a little, incongruent in the context of this music, which was composed for the accordian like bandoneon (a woefully inadequate description). Tango came from the street not the parlour. Ma has unwittingly sanitised the product and watered it down a little as a result.
If you like Ma's work, this is a prefectly serviceable CD but, if you wish to hear Piazolla's work at its best, find some performances by the composer himself and revel in the energy and the passion. YOu could, of course, buy both.