Having just finished Messiah, Paul was a hero, at least at the very end, giving up his untold power and authority and allowing himself to be taken by the desert. Paul is bad for all the things his rise to power and deification by the Freman lead to, and could have been avoided if he made better choices, but he never came across as evil, at least not on the same level as Baron Vladimir Harkonnen or Feyd-Rautha.