Nah, it was the script. Too many exposition filled and motivational speeches, not enough quiet real moments, and too disregard for collateral damage.
And the main issue is that it was written and styled like a Nolan film, and Snyder (clearly) wasn't allowed to fully make it his own.
In other words, Snyder was given a Nolan type story/script (though without Nolan's writing to polish Goyer's work; THE fatal flaw), and apply flashy, VFX based action to it (something Nolan isn't known for and didn't feature much in the TDKT).
It's what everyone expected, but it didn't work. And you can tell he was given much more freedom with BvS than MOS, given how stylistically similar BvS is to his pre-MOS films, whereas MOS was very removed from those efforts.