Corwin

Actually a neutron weapon is reviled because it's a horribly vicious weapon. It isn't really even a bomb per se.... it's a hard radiation emitter. (No actual explosion, just a burst of free neutrons.) They're pretty short lived, and decay rapidly... so the long term effects are minimal to the environment. (This is why it 'leaves the buildings intact.') People, on the other hand, suffer extreme radiation poisoning. Lesser amounts of radiation would probably give them cancer... but this dose is enough to break down most of the enzymes in the human body and the systems that produce those enzymes. (As well as wreaking havoc with the victims' DNA.) Without those enzymes, the body just starts to shut down, one system at a time.

All told it generally takes about three days to die, and it's pretty agonizing. It's an extremely vicious and brutal weapon, even worse than biological or chemical agents.