The main problem with “Mama” though is that in terms of story, it’s the same old shit that we’ve seen in every other paranormal flick out there. The only parts which leave an impression- the weird attempts at humor and the sudden transition from horror to fantasy- only stand out because they don't work.
It is so by the numbers and conventional that you almost start to wish that it was atrocious, so you could actually feel something about it. Instead, we just have to wallow in its mediocrity. The big shocker is how they somehow roped Kevin Costner into participating in something so blandly forgettable.
It's like the filmmakers got together and announced their ambitions as: “Let's make every haunted house movie ever made!”. So began long periods of research where they gathered all of the cliches together and created the monster known as “Dark Mirror”.