Short version: Justice League, perhaps surprisingly, did not actually suck. There is even a hint of a suggestion that the people who put the movie it may have tried to have fun in the process. I dunno just how much each one of you have felt betrayed by DCEU to date, but this is at least matinee-worthy.
Somewhat longer version: ach, well, it’s not a Marvel film, for better or for worse. I’m not going to get in on the relative merits of DC vs. Marvel comic books (largely because I was always on Team DC, so I’m obviously prejudiced there) but there are things that one IP can do more easily than the other, and vice versa. It’s hard for Marvel movies to achieve gravitas, and it’s bloody difficult for DC ones to shed their excess. If Justice League was trying to do anything else, it was trying to get out from under the gloomy nature of the DCEU films that preceded it. And I think that it did a better job than I expected it to.
Also: the movie actually rectified a nigh-constant complaint that I have had in the past. I won’t say more because spoilers.
Midnight’s Edge put out a video explaining what went wrong with the Justice League movie and the DCEU as a whole.