No surgical procedure is safe, just like no rocket take off is, despite how advanced the technology is. Hear transplants depend on the same theory used 100 years ago, the only change is the integration of technology that prevents mistakes from happening. It is the human mistake that brings risks to any sort of procedure that involves the risk of a human life. From the talks I had with other neurosurgeons from around the world, the theory behind the procedure is plausible, but the amount of mistakes that could be made at every step is countless.