Really liked the finale, especially Obi-Wan and Vader's scenes. Where Kenobi truly sees what Anakin has become, and lets him go.
More items of note:
-Obi-Wan going for the respirator control box! Attack his weak point for massive damage!
-Vader's horrible gasping when his mask is broken open, and the dialogue between them that follows; top-shelf stuff. Great performances from both McGregor and Christensen here (plus some good lighting; a bit of blue on Vader's face as he absolves Obi-Wan of killing Anakin, then red as he vows to destroy him).
-Vader's projection of power and strength is remarkably fragile, which is important. Like so many strongmen he relies on never being caught in a moment of weakness.
-How Obi-Wan once again walks away from a defeated Vader, leaving him alone and smoldering. (Yes this leads to Vader killing more people, of course, but as a character beat it's spot-on.) Vader never defeats him, not even once; like Kylo Ren, he's forever left unsatisfied when his nemesis just sacrifices himself and vanishes.
-The way Obi-Wan freeing himself from the pit and lifting all those rocks to throw at Vader calls Rey moving rocks in TLJ to mind.
-Pretty much everything in the episode after the duel, too. The scenes with Reva, Leia, Owen and Luke, all great stuff.
-Reva's thought process on killing Luke as some form of justice is a bit muddied, but I'm glad she comes to her senses on her own.
-Owen and Beru getting their rifles and facing down a pissed ex-Inquisitor is great Western stuff.
-Funny how they had to have Luke escaping out a hatch or getting knocked out so he couldn't see the lightsaber ever (he doesn't know what one is in ANH, seeing his father's for the first time). Not quite at the level of keeping Anakin away from Grievous, but still funny.
-This is very solidly episode 3.5, IMO. A newly essential part of the prequels.