This isn't going to be a long and detailed breakdown of the Ultimate Edition, however there are some spoilers ahead. I'm not going to go through every subtle difference in intricate detail. But I am going to explain why I think the Ultimate Edition is worth a watch.
First of all, if you haven't seen Batman v Superman, don't bother with the theatrical cut. Go straight to the Ultimate Edition, it's by far the better version and not just because it's longer. The Ultimate Edition is what Zack Snyder wanted us to see, but it was cut for a lower age certificate and a shorter run time. Now I'm not sure that the changes are enough to make those who passionately hate the movie change their minds. But those who don't like the theatrical cut may be impressed by the changes, of which there are many. The extra thirty minutes go a long way towards plugging the gaps and plot holes in the story, including what happened in Africa and the aftermath, Clark's trips to Gotham, the implications of the "Bat Brand" and Lois' investigations into the mercenaries and the mystery bullet. Does it solve all of the problems? No, there are still some issues, but show me a movie that doesn't have issues.
|Clark heads to Gotham to see one of Superman's accusers|
|Clark is warned about the Batman|
|Jena Malone plays a scientist who analyses the bullet for Lois|
|Lex's "Communion" with Steppenwolf - "the bell has already been rung"|