I certainly found him more sympathetic than the witches themselves. In the movie, they are complicit in Nicholson's character's crimes, including murder, and happily use his demonic powers. They suffer absolutely no comeuppance, end up much better and happier than before they chose evil, and also banish and enslave Nicholson by the end, while they each raise the son they had with him, with Nicholson watching helplessly on a television screen, a demented matriarchal society.
It's a sick feminist power fantasy.
Apparently, the book's plot is significantly more interesting, balanced, and rightly presents the witches as the villains that they truly are; https://en.wikipedia.org/wiki/The_Witches_of_Eastwick
Amusingly, the author John Updike claimed the novel was an attempt to "make things right with my, what shall we call them, feminist detractors".
Well, the movie adaptation multiplied that factor by an order of magnitude or two.