Not that bad
He got blamed for how his son turned out but his influence had been overly exaggerated. None of his other children turned out as messed up as Michael.
There is a 2007 documentary called "what really happened" and it was revealed that the abuse showed to Michael as a boy was highly over exaggerated. How also never stole from Michael and actually help him put away money as a boy.
Joe Jackson did use the belt, this is well known and he did demand arguable "perfection" in terms of the performance from his sons but this lead to them getting out of Gary and having careers. Without Joe's enforcement there would have been no Jackson 5.
Joe also did not pick on Michael's looks as much as what's been reported. He commented on his sons acne and larger nose because he warned him that the industry is superficial and that he had to "look like a star". I think Joe was being blunt. I don't think Michael's plastic surgery had too much to do with Joe's comments. Michael just seemed to want to look like a white woman... Which Joe was not responsible for either.