My late cat wasn't neutered, vet did not want to take the risk, me neither. Got it as a very sick rescue. He must have fathered a few, because on anti-biotics, he was the top cat of the street.
It worked like speed.
In areas with houses at close distance a non neutered male cat can be a nuisance. He may not spray at home, but in houses of others. He may wander further and further, because of lack of non neutered females in his surroundings. So, in a village as mine, I think neutering is not a bad thing. My next door cat did become a bit more meek because of it though. Not much. He is slightly less aggressive.
Both my cats now were already neutered before I got them. They still both catch their mice and sparrows. Don't know if they changed a lot with the neutering.
Another male cat in my neighbourhood got neutered because he was found very sick, and apparently abandoned (found on one of his week long straying trips) by pet rescue. The owners were livid. The others in the neighbourhood kinda relieved. He sprayed in all houses he could get access too. So, he got a lot of aggression of people towards him. His personality did change. From very frightened to an outgoing cat. He still breaks his entries though. So, not a complete change. He does not spray anymore. And he doesn't stray for weeks any more either.
