Okay I just got done watching this, and I loved it. I don’t think I’ll be able to go back to an unmerged RotS after this, it just meshed so perfectly in my opinion.

Only two minor issues stood out to me:

The scene where Obi-Wan has a hologram conversation with Ahsoka, are you sure that scene is supposed to take place after Obi-Wan arrives on Utapau? The way he says “I’m being sent to hunt down General Grevious on Utapau”, makes it sound like he hasn’t gone there yet. Would this scene fit better a bit earlier, right before Obi-wan leaves?
If you decide to keep the final Vader scene as a post credits scene, I think you should have it fade to black at the end. It currently ends abruptly, which is awkward.

Now I just really need a movie edit of Rebels so I can have a more concise conclusion the Vader/Ahsoka and Obi-Wan/Maul story arcs without having to sit through all the filler.