i've never tried soy protein. i hear both good and bad things about it. i believe it to be ok. dont expect anything spectacular from it or any other supplement you take. its just protein in a powered form.
you want to get big, muscle wise; this come from you, not a supplement. dont fall prey to the hype. supplements are useful, i use plenty myself but i dont look to them for my gains.
how do you get big? training, nutrition and rest/recovery. you train the muscle, you feed the muscle, you rest the muscle. sounds simple, right? well, the approach is simple, but putting this all into play is hard work.
besides training, nutrition and rest, remember desire, discipline and commitment. the desire to want it, the discipline to do it and the commitment to get it done.
now get to work!!!!!