It's good in that it gives you a very hard neutron spectrum (good for efficient breeding) without being chemically reactive. It still has potentially unsolved problems in corrosion, required pumping power (i.e. power density limits) and erosion. There's been some recent work on oxygen control that really helps with the corrosion issue.
Thanks, I was wondering the issues around corrosion and servicing were being addressed. It always seemed like the best hope for a balance between a good breeder reactor, and non-proliferation concerns to me.
