It's the same movie.
It goes much smoother though, the investigations are more fleshed out and the Batman/Superman fight has more meaning to it beyond Lex telling them to. That being said, if you thought Clark Kent didn't get enough time, you may be pleased, but if you didn't like the way Superman was done, he's not done any differently. The fighting isn't more visceral, in spite of the R Rating. Honestly, it's not a different film.
It's the same movie.
There are some clips here or there, but some pacing issues still exist. Case in point, the Knightmare scene. I don't know why this scene exists in any cut of the movie because of the way it occurs. The Man-Bat scene. Both of those scenes needed to be cut out of this cut and better stuff should have been added in. We did not need extra scenes to the Knightmare sequence, that needed to be gone altogether and Zack, we know you filmed three and a half hours of footage. You had better footage to fill it in with.
It's the same movie.
There are like two extra characters we didn't see who serve to flesh out Clark Kent's investigation into Batman and Lois Lane's bullet investigation. Again, if the bullet investigation peeved you off before, it will do so now. Clark's investigation, though, is pretty interesting and may actually make a lot of people happy. Oh, and of the other snippets here and there that you see, one of them includes a shot at Ben's ass, so there you go.
So will you like it? If you hated it, no. If you loved it (I did), yes. If you're mixed, on the fence, it could either push you into the ocean or get you to jump to the side of love. Again, it's like the extended cuts for The Lord of the Rings, there is a lot of stuff there that fleshes out the film, but it doesn't change it. The movie is still what it was before, just more detailed. Is The Fellowship of the Ring extended drastically different from theatrical? No. It is much more refined, polished and articulate, though. That's what you get.
You also get a better look at Chris Terrio's contribution. The movie is credited David Goyer and Chris Terrior - which indicates that the two did not work together. It means Terrio took Goyer's screenplay that was developed with Snyder and retooled it. I say this because you can tell that Terrio's retooling was done to alter the movie into leading up to Justice League and to make it quotable. I mean, love it or hate it, the screenplay is indeed quotable.
Personally, I give Batman v. Superman: Dawn of Justice Ultimate Edition an 8/10. Critically, it's a 7/10 - there are still issues with the film, in part because it doesn't change drastically but in part because it is smoother if anything.
Oh and the animal in the thumbnail is a Dimetrodon.