First of all, anyone reading this review should know I'm EXTREMELY forgiving with horror films. If you have half-decent character development, a semi-plausible plot line, average actors or better, good FX and AT LEAST one or two "gotcha" moments, or some combination thereof, I'll give it a good recommendation.
Sadly, The Bye Bye Man has none of it.
Let's start with back story - there is NONE! (apart from some journalist encountering BBM 30 years before the story takes place). We do not know who BBM is, where he came from, how he came into existence, or why he terrorizes people. This is the biggest flaw that sinks the movie. Perhaps the filmmakers thought if they tell you NOTHING about the boogieman, it will make him more scary. It doesn't - it's disingenuous, at best.
Half of the actors give wooden performances, and the other half overact grandiosely. I was particularly distressed to see Carrie Ann Moss and - GASP! - Academy Award winner Faye Dunaway, as they are so much better than this material. I got the impression the producers wanted big names to attract an audience (and maybe Ms. Dunaway really, really needs the money). It was difficult to care for any of these characters.
The plot is ludicrous and revolves around the single notion "don't think it, don't say it" which, if you analyze it, is antithetical to how people behave. You've got a supernatural boogieman after you, intending to kill you, and you're not going to think about him?!?! C'mon...
I did not have one single, solitary moment when I felt tense or ill at ease. There were NO "gotcha" moments for me throughout the entire picture, which I found all too predictable. For example, the filmmakers conspicuously place a robe in the bedroom of the two central characters and make it the main focus of the camera angles in several scenes, so that when it comes alive as the BBM, it's simply a yawning moment. In fact, the few times BBM was presented, I was appalled at the lack of creativity in trying to make him anything close to menacing. Makeup and costumes were extremely lacking, as if the filmmakers chose to chop those expenses to meet budget.
The only injustice I can think of would be to make a sequel of this mess.