There are great parts, good parts, and bad things that were disappointing.
Music selection - as always gunn is epic with this
Nonsensical story parts - It made no sense that we introduce Lois and Superman are dating and then immediately follow that up with her asking him for an interview and getting into a giant aggressive confrontational fight from the interview right off the bat. It kills the vibe and any sense that they have any social intelligent and any real type of possible relationship. If you can't even know when to cool it down off the bat and it's clearly going off the rails, this is like completely something most people would pick out and reject someone on the first date for.
Most scenes with antagonism/challenges are solved quickly without much challenge, usually not by superman and superman's involvement is meh - he would have no chance or brainpower to be able to come up with the physics or tech necessary to escape that pocket universe if Mr Terrific wasn't there. And so he just got lucky. And if theyre always getting lucky in the nick of time, it becomes unbelievable. He would've just escaped out of the jail and been stuck there 99% of the other time. And he did almost nothing to convince that shapeshifting dude to change sides when this guy was so again it and was screaming at him to stop talking to him. All it takes is seeing one random stranger die and he has a change of heart. WTF? I do give credit to superman for beating that clone of him at the end but the other stuff was meh.
Multiple random bits of stuff that made no sense and just left you confused or the plot less smooth and believable - the random average reporter guy with the super hot girl that is dating lex that just is obsessed over him but he isnt into it. that was never explained at all but at least they had lois acknowledge it. all the horrendous things lex is doing in the pocket universe including murder and the government just lets him do it unmonitored. and he just makes his ex 'disappear' and be tortured in the universe because she wrote a blog about him and the world just allows it and doesnt wonder where she is missing off to. and this woman is tortured and probably starved and socially isolated in this pocket universe jail so much and she still happens to be so loyal to lex that she starts tattling on the cell next door immediately when they do something fishy? hell no! that is her one chance to escape this eternal jail! she would've let superman do his thing. (funny enough he didnt get rescued because superman couldn't go back even though he wanted unfortunately)
Other superheroes - I loved Guy for green lantern and mr terrific. great powers and personalities. didnt think i would. i dont like they call them metahumans but whatever.
Lex luther - great actor and he nailed the role but I wish they had a much more muscular tall version of Lex with a deep voice like in the comics who was more of a confident arrogant genius rather than a sniveling skinny guy with a shreaking high voice
Casting for Superman - really great. The version who is clone with long hair really looks like Henry Cavill! So they did a good job replacing him. He adds a more warm comfortable relatable feel to him than Henry did which is great.
Overall - better than the Man of Steel by far. That old DCU film was garbage in comparison.