Nicolas Cage reviews Justice League in five simple words for Variety, "I thought it was fun." He doesn't go beyond that, and then laughs about the fact that he's not going to go beyond that. No film franchise seems to be as divisive as the DC films these days and Cage knows that if he were to go into further detail of his thoughts on Justice League he'd be opening a can of worms that he really doesn't want to get into, regardless of which side of the fence he fell on.
From there, however, things get even more awkward when Nicolas Cage is asked about the possibility that he might ever play Superman. He shuts down the idea hard, saying he doesn't think about himself ever playing Superman "at all." It sounds like he has so far removed himself from the idea that even considering the question or being asked to review a movie he happened to see has him a little back on his heels.
As popular a character as Superman is, bringing him back to the big screen after Christopher Reeve's run was a difficult process. The most famous "almost happened" story about the character saw Tim Burton nearly direct Nicolas Cage in the title role. Images of Cage in a Superman suit have traveled around the internet since then, so we know exactly how close things came to happen. Also, Cage named his child Kal-El, so there's really no way to understate just how big a fan of Superman the actor is. One has to believe that not playing the part is something of a sore subject.