Sally Fallon and Mary G. Enig Ph.D have written a telling story about soy's sinister side-

A major work defining soy's dark side states that the use of soy protein isolate (SPI) in "animal feeding experiments, increased requirements for vitamins E, K, D and B12 and created deficiency symptoms of calcium, magnesium, manganese, molybdenum, copper, iron and zinc. Also, soy products greatly inhibit zinc and iron absorption; test animals fed SPI develop enlarged organs, particularly the pancreas and thyroid gland, and increased deposition of fatty acids in the liver.
Yet soy protein isolate is used extensively in school lunch programs, commercial baked goods, diet beverages and fast food products. They are heavily promoted in third world countries and form the basis of many food giveaway programs.
Numerous artificial flavorings, particularly MSG, are added to soy protein isolate products to mask their strong "beany" taste and to impart the flavor of meat."

If there were nothing else to consider except the addition of MSG, (anything but a healthy additive,) that alone would be enough for me to reconsider eating soy products.