aside from cavills mouth, the CGI was pretty much on point with every other marvel movie out there so if hes knocking it for that, he needs to re-access what he considers acceptable CGI.

also, it was quite nicely done. unless you know somewhere on earth we can get a red sky and shoot it in natural light. cyborg was done well too although some of his scenes were cut and replaced because whedon. steppenwolf wasnt weak because CGI, he was weak character wise but again, thats probably because they reduced the movie time to 2 hours so you dont quite understand his character fully. all you know about him is he wants to teraform earth for darkside using mother boxes, nothing beyond that.