I think the majority of the reviews online have been able to pinpoint the flaws/"Hate" fairly articulately. The "hate" stems mostly from a few things that stick out like a sore thumb in the movie... For instance...
To name a few.
But the big two are:
- They are trying to "catch up" to Marvel with the "Team Movie Genre" without trying to build any of the structure, and the movie feels bloated AND rushed at the same time for it. This could have been 2 or 3 movies with the plot lines involved in the movie. (This complaint originates before the movie even had it's first trailer... But sadly the movie itself adds fuel to that fire of the criticism because not only did they decide to make a team up movie right away, but jammed so much in it that it basically is a set up movie with some plots thrown around it.)
- Marvel/Disney understands their characters and audience better. They try and stick to the formula's that made the character who they are. Snyder doesn't care and does what he wants. There is plenty to be said about "Artistic vision" and the like... But not for 50 year old iconic characters. You can find ways to modernize them, but you can't change them.
Now, using Marvel/Disney as a reference against the movie may sound a little fan-boyish or bias... But DC/WB has taken the wrong lessons from Marvels success, but wants the same success... But they are lacking the one thing that Marvel/Disney are doing ( and more recently even Fox): Respect for the Character and Lore, of which they have shown near zero for in the two movies they have for this universe so far. Sure they have USED lore... But with no respect for it.
But don't get me wrong, people think a 5 out of 10 means it's a BAD, TERRIBLE NO GOOD MOVIE... When in actuality, it means more along the lines of "Meh, it's average. Good and bad, but nothing great etc...". We've all come to expect different things out of rating systems, and it's kind of sad that everyone thinks anything below a 6 or a 7 is pure garbage. And of course, there was no question that it would make a bunch of money... at first. But whether it has the staying power is the question.
This is one of those movies that could possibly have scored a bit higher if there already had not been something superior doing the same thing, only better... But we do. And they have 13+ movies and 4+ CONNECTED tv shows that are ALL positively reviewed ( Thor 2 (66%) and the Hulk (67%) are the lowest)... While DC has 2 out with negative scores and 2 more coming... One that is getting re-shoots no doubt because of BvS's dismal reviews (Suicide Squad).
And say what you will about Christopher Nolan's Batman films... But they were not "Comic book" movies. Sure he used a comic book character, but he made him for the real world. It worked for that series, but it doesn't work for a world with Superman and Wonder Woman.
So yeah, I think all the "hate" is pretty well deserved and understandable.
Was it still entertaining?
Sure.
Was it a good superhero movie that respected the lore, and who the characters are? ( or even respect the current movie industry?)
Nope.