Personally, I would have gone with another Apokolips new god given the chosen storyline for the movie. Desaad would have been a better choice I think. Perhaps even Orion.
That said, I thought Steffenwolf was a prime League adversary for an introductory Darkseid chapter. Ciarán Hinds voicework was not excellent but pretty good in my opinion. I did think the CGI quality of his onscreen character was a touch off. Kinda messy. Not clean like The Hulk in the Avengers movies.
Overall, the antagonist was not the issue for me. The wishy-washy script and presentation was. Barry Allen was the prime example of wishy-washy. For me, Cyborg and Aquaman were above average decent for the movie and I have zero problem with Gia Gadot's Wonder Woman throughout the movie. And I have made my opinion known about Ben Affleck.
Comical, for me, was Henry Cavill's Superman. Ditching his darker blue suit for the lighter blue version. Same for the music backdrop of Kal-El's mini-fight with the League at his memorial. The whole 'Truth and Justice' pre-speech before fighting Steffenwolf for the first time. The lame 'I want to die again' joke after prying apart the Mother Boxes (did like WW's 'I work with children' observation though). Heck. I think my best feelings about Superman in the movie was his time with Lois Lane, seeing his mother, and his race with The Flash lol.
I gotta start thinking happy thoughts about the sequel, although I doubt I can jinx it anymore than I possibly could.