I've only read a few reviews and it seems the major criticism is of Zach Snyder. Evidently Affleck does a decent job, I definitely wasn't rooting against him. A bad superhero movie is a huge bummer.
I hope it doesn't bomb, because I would love a quality justice league movie or two, but perhaps if the criticism is bad enough maybe they can take the keys away from Zach Snyder.
Marvel has done a solid job of putting out a quality product, why DC/WB would give the keys to the entire kingdom to the guy that directed Sucker Punch I just don't know.
I really hope Suicide Squad is better, it definitely looks more fun, and that's what superhero movies should be...fun. Deadpool is the most fun I've had at a movie in a long time, and it's exactly what I wanted. Guardians of the Galaxy as well...just plain fun.
Evidently they crammed too much in, so it suffered.
Based on the Lego Batman trailer they should have done Lego Batman vs Lego Superman: Lego Dawn of Lego Justice