The short verdict is: “This is way better than any of the Avengers films. If you’re tired of these Avengers films or you hated their wink-wink vibe and nonsensical city-on-jet-boosters plots, wished for something that still has humor but has a bit more seriousness to it, then Justice League should be right up your alley.”
This isn’t a perfect film to be sure. The biggest problem I have with it is that it relies totally on BATMAN V SUPERMAN, but even then Snyder uses careful bookending just so that he respects people who might have not seen BVS, not in terms of information, but at least in terms of action ramping - this is something the Marvel/Avengers films frequently fail to take into account. You are at least shown some lead up towards things or story milestones, even if the complete information is tucked away in a previous film. This is different from Avengers films that seem to move on from one thing to the next with no regard for easing the audience into the main action.
The film follows a slightly darker version of the kind of tone set in Wonder Woman, and for practical purposes, rooting much information and plot items into BVS is a way to allow the film enough time to setup each of the characters.
This is another area where this film is a better take of the superhero ensemble film. Each of the characters is important to the key plot of the film. Items are all rooted to either the Kryptonian technology (or technology, science, or biology from the Kryptonian side of the universe), or Batman’s Earth bound world of governments, technology, and military hardware. That goes for all the characters, save Wonder Woman and Aquaman - though both are kind of explained as human-labeled super races in a Universe that is populated with them. This isn’t like some ensemble film where characters have to be forced together, other than a slight leap to believe that Atlanteans and Amazons can be counted as Earth-bound “tribes” of superior beings.
So in that way it feels more like a Superman and Batman movie with more supporting characters, and not a mish-mash of superstars. Viewers who prefer a more rooted experience will find this move to be quite palatable.
The story, in turn, carries to a subdued extent the notion that the Universe is full of similarly powerful beings from distant worlds, not all of which are as benevolent as some of the ones found on Earth, and one of them that was raised among us.
I saw no signs of “poor Batman portrayal” for anyone worried about that. I felt this was still a continuation of a very good interpretation of Batman post-CrimeFighting career. Without Superman for much of the running time, this is mostly Batman’s movie. Wonder Woman is present, but somewhat less on the forefront due to personal issues that were established in the Wonder Woman film.
Some of the humor looks like the result of Whedon’s taking over of the helm, but it’s not overpowering and is great for establishing the personality bases of the characters. Many reviews focus on the Flash’s part as comic relief, but I found that the addition of humor was a great balance for Superman as well which helps conjure some threads of the character that go back faintly to the more noble and good natured version of the character from the comic books and the Donner films. There’s even a hidden musical tribute to Richard Donner’s Superman if you’re really attentive.
Careful eyes and ears will also catch homages of Batman that go back to the Tim Burton versions, but make no mistake this film is firmly rooted on Bruce Wayne dealing with a world he no longer recognizes, but must be saved regardless. It’s a version of the character that is still carrying the gravity of having played some part in Superman’s death, and when there is some possibility that Superman can be brought back, he honestly admits that one of the reasons he would like to see Superman return is because Superman, despite being alien, was a better human being than Bruce Wayne was. This emotional drive is coupled with a growing calculating side to the Bruce Wayne character - because he must be smarter to try and come to terms with both his advancing age and the advancing nature of threats - and he has basically figured out that without Superman, the world would be doomed regardless of their efforts.
In-fiction consistency in this world is pretty strong. When it is finally revealed in what way Superman can be brought back. It is immediately apparent that it is a terrible, 99% superbad idea. That stamp isn’t handed out the way it normally is in movies where people say “This is a bad idea”, by following in-fiction logic, and dealing with the Man from Krypton it really comes across as the mother of all bad ideas. Again, this is something superior to the Avengers films where you know all the gags are being delivered behind heckles and lulz and desperate Hail Mary plans carry no tension at all.
There is also a sense that the guys who put this film together are big fans of the Injustice video games. The designs, color palettes, and even the action seems to be inspired by the popular series of fighting games. This adds a visual dimension to Batman’s calculation of the odds. By following the power levels in the fights, you do figure out that “without Superman the world is doomed”.
I found it all quite entertaining, and I don’t mind seeing it again anytime soon.