I feel like the big scary problem is capturing the heat. The proposed method I've seen involves a beryllium "blanket" that captures the heat to send it off to a boiler. The problem is beryllium is quite expensive and quite limited in availability. And in fact we may only have enough beryllium (in the world) for a dozen or so reactors. But it's worse, because these blankets absorb high energy neutrons, and become radioactive over time. And that means two problems, you need to replace the blanket and you need to dispose of radioactive waste.
When you put all that together, I just think "shouldn't we stick with fission power?"