Ok, I don't really understand the criticism of this movie. First of all, take it for what it is, a cool super hero movie with a big budget and very cool CGI. I really enjoyed the action, especially in the theater. I just watched it again at home to see if I missed something given the poor reviews and box office performance, and, nope, liked it again on the second viewing.
Perhaps they did too much background stuff for the casual viewer, hoping that they could connect lore dots such as the origin story of Hawkman and Dr. Fate (look it up).
The action was great, the one liners very well timed, and the plot was simple but filling for an origin story.
Give it a rest folks. Had this movie come out before the time of hero fatigue, everyone would have been giving it high ratings.
It's a fun watch and I recommend it.