I think that it depends on how heavily scripted the 'hero' is. Many games allow you some flexibility of action and choice, but others dictate your responses too heavily, to the point where it is jarring. I like games that provide a rich experience for whatever 'alignment' you choose - that was one of my biggest issues with Oblivion: it felt like it was meant to be played once as good / neutral / evil all at once, taking on fighter / mage / rogue roles …