What are some of the good and bad effects of you hitting your children every now and then?

There is no good effects , absolutely none
The effects are :
You teach them that violence is love
You make them fearful and eventually resentful of you
When they are old enough to hit you back they may
You teach them that violence is a means of resolution they may use later on when faced with problems in their partnerships or own children
It's lazy and hence easier to implement than trying to understand a child and acknowledge them as their own individuals with their own feelings
You teach them that feelings deserve to be punished and repressed