I think people will see the total lack of the Emperor in ANH as strange, given he's very prominent in Ep 1 to 3. I suspect that there will be some kind of Vader-Emperor scene in ANH edited in, also to explain why Bad-ass Vader suddenly plays second fiddle to Tarkin.
I hope there are no more changes. There don't need to be anymore, unless he makes Han shoot first. 
I don't think it's strange that the Emperor isn't in ANH; I think it adds depth. Even though he does not appear, his presence is still felt. Vader is still there, the Empire is strong, and Tarkin is running the show, This isn't a weakness at all. It would be weaker if the audience had to be reminded about the character. This lets the audeince use their imagination, and piece together information that isn't present. Yoda is not in ANH either, because it would not make sense from a narrative perspective to just insert him. In the first LOTR's film, we don't see any Ents, yet that does not lessen their impact once they appear in the second film.
No offense, but that last bit is a really dumb statement. You try to make the appearance of some character be the same as the lack of a character in one movie after 3 he was in.
You didn't have 3 movies with ents, then one without, and hey, number 5, they're back again.
... also to explain why Bad-ass Vader suddenly plays second fiddle to Tarkin.
Admit, in ANH, Tarkin is the main Bad Guy, and Vader is his evil ruthless henchman.
That does not gell with Ep 1 to 3, and 5 + 6.
I think it gels very well, hence the tragedy of Vader is more palpable; in spite of all his power, and attempt to gain more, he is still under the Emperor's thumb (just as he thought he was with the Jedi council), and under Tarkin's "leash" (to quote a certain Princess).
Myeah, your POV. In my view, Vader runs the show in TESB and ROTJ, while in ANH, he really is just some dumb dog for Tarkin.
In TESB, he can unleash all his power, like he did in ROTS. So why oh why, would this tragic hero, this troubled mind, submit himself to being bossed around.
He is the right hand of the Emperor, he helped create the Empire, he secured the Empire by wiping out the Jedi, why would he be content with being told what to do by Tarkin in the way he does in ANH?
"Vader, release him" "As you wish."
Myeah, really connects with that rage Anakin has in ROTS, and what he also shows in the duel in TESB, just before he severs Luke's hand.
But again, your POV.