* one early bomb is more or less equivilant to one conventional HE + incendiary raid.
* 2,000+ other bombs have since been detonated, a good number of which were orders of magnitudes more destructive than the early "first gen" bombs used on Japan.
Nuclear war with the larger weapons that followed would be considerably worse than incendiary bombs, in physical destruction, in immediate deaths, and in injuries and following mortalities.
Using nuclear weapons only tactically against counterforce targets would not be that horrifying.
I can't register a difference between a nuclear bomb and, say, a GBU-12 Paveway conventional bomb. They both destroy and kill brutally, the magnitude is irrelevant and it would be great if we never have to use either of them.
Let's compare using Wikipedia as a source:
Mass killings of large civilian populations should not happen. I don't personally see nuclear weapons as worse than incendiary bombs or artillery. It's the number of casualties that makes it horrible.