Part of the problem is probably that we see Vader having become one with the Force at the end of Episode VI
Except because of the way the movie is as viewable now we DON'T, we see Anakin. Which I think is actually a pretty good change (sucks for the Vader actor though). We see that thanks to killing the greater evil in Palpatine and through Luke's love, Vader dies and Anakin is saved
But none of this wipes his slate clean and I imagine his eternity will not be a quiet one