He might have been a decent (for a certain value of decent) ruler but as a person he stunk.
Are you referring to Caesarion? He was just a teenager when he was killed so I don’t think we know enough about him to know how he would have turned out. At the end he would have been content just to have his life spared, but Octavian, the adopted son of Julius Caesar, didn’t want any biological sons of Caesar around. He would not have had any legal claim in Rome as the illegitimate son of a non-citizen.