Why is Srila Prabhupada special? - Of course, personally he is my beacon of light. I have not seen any person (not exaggeration) as intelligent and humble as Prabhupada. That being said, the point here i want to make is among the jet paced global spiritual gurus of his time, I think Prabhupada was the only person who was not afraid to call a spade for a spade.
For those who were serious of spiritual life, like an expert doctor, he clinically isolated the bad from the good. Prabhupada was not afraid to point out bogus philosophy, watered down vedanta, pure word jugglery and outright cheating. After clearing the dirt, Prabhupada injected pure organic vedanta as have been taught through the ages without adulteration. This style of presentation of God was actually a systematic scientific presentation found only in academia.
Prabhupada presented the topic of God with such clarity (distinguishing the fake from real), it was hard to find fault. The only way one can disagree was if one simply was not interested in the real message of God. Even today, so called spiritual gurus beat around the bush explaining the metaphysics of life. I don't think there will be anyone as clear as Prabhupada in explaining the science of God.