No-one can have failed to notice the splash that induced pluripotent stem (iPS) cells have made in the few years since somatic cells were first reprogrammed to pluripotency. But what is their real promise, where should research efforts be focused, and are we at a stage where we can replace embryonic stem cells? Four pioneering iPS cell researchers offer their personal insights into these and other questions of current debate. As well expressing hope for the improved understanding and treatment of human disease, they urge caution over safety and propose the establishment of iPS cell banks.