Batman v Superman (2016)
Reviewers hated it, but viewers didn't think it was quite that bad with a 27/68 on the rotten tomatoes meter. And for free, it wasn't bad at all. It was long, and wasted too much explaining who Batman was, and flashbacks and dream sequences were heavy handed. It had sort of a weak-sauce on why do these guys wanna fight? Who put Metropolis and Gotham across the river from one another, and why did the super-heroes and criminals not cross over more? But as my wife would say, "THAT'S what you had a problem with in that movie?"
So if you like the characters or Universe, and you want to watch a very long prequel setup film for the Justice League (hence the subtitle of "Dawn of Justice"), it's not nearly as bad as Fantastic Four, Green Lantern, Daredevil, or Supergirl.