While the Ultimate Edition does make some parts make more sense, those parts still aren't that necessary. I actually think the movie needed to cut a lot out.
Here's what I'd cut from the movie:
-Cut everything in the Africa scene before Lois being unmasked.
-Cut the KGBeast parts of the Africa scene, including the conflict between them and the terrorists and the framing.
-Cut every Kahina scene.
-Cut the scene of Lois coming home, opening her mailbox, and sitting around looking at a bullet, and the bathtub scene (maybe work in the romantic shots into another scene as a brief flashback, perhaps when Lois is given the ring at the end)
-Cut the lab scene with the bullet, Lois barging into the meeting regarding the bullet, and Clark warning Lois about digging up snakes
-Cut both Lois/Swanwick scenes
-Cut the bit where Bruce discovers his drive has been stolen. We can assume he retrieved it.
-Cut the second Diana/Bruce scene where he gets the drive back. Their flirtation doesn't amount to anything in this movie.
-Boil the Knightmare scene down to quick flashes of the "important" stuff: Bruce using guns, Superman soldiers, and Superman killing him.
-Have Bruce watch the videos, not Diana.
-Remove Diana reading Bruce's email. Whereas Bruce watching the videos feels like it could add to Bruce's fears, especially right after the Superman Knightmare, the email scene feels like Bruce's attention is divided. An email is also too cordial given his 1% mentality towards Supes.
-Remove the part with Diana on the plane.
-Remove the Steppenwolf scene. As is, it interrupts the effect of Superman's death, which worked better in the theatrical version. Instead, edit parts of it into Lex's prison scene with Batman, overlaying a couple shots of his Steppenwolf encounter while he's explaining about the bell being rung.