Another problem with fission is that there is a limited amount of uranium available. Apparantly the prices are already going up. Now, we are not likely to run out any time soon (the estimates seem to range betwen 50-100 years) and presumably new deposits will be found, but that does not change the fact that fission -like oil- is only a temporary solution to the worlds energy problems.
Moreover, there is no way to completely separate civilian and military use of fission; if we want to world to use more nuclear power we will have to accept that ALL (or at least most) countries will need to have nuclear power plants of their own and quite a few will have to build enrichment facilites that can -in principle- also can be used to make weapon-grade uranium. Another problem is of course that even a civilian power plant can be quite dangerous if it ends up being located in the middle of a civil war, someone is bound to figure out that a nuclear meltdown is quite an efficient method of killing a lot of people and force any surviors to leave the area.