sonnyboo said:

For Luke to sense, invisible to the audience and not demonstrated by any action or even words spoken that Darth Vader has some 'good in him' is just plain POOR FILMMAKING. There are a myriad of things Lucas (or Kasden) could have done in the screenplay to DEMONSTRATE some wavering from being totally evil. As it is, from episodes iV-V, this comes out of left field and makes no sense.

Well, the strangulation bodycount was considerably lower than before. Vader's got that going for him. ;)