I saw this film in the theater opening weekend to avoid the spoilers that would eventually spill out into media. It is easily one of the worst movies I've paid to see in recent times; and there is so much wrong with it I wouldn't even know where to begin ...
...maybe I do actually: Wahlberg being badly miscast as the mild mannered teacher. His acting choice was to recite lines as if he were doing a guest spot on Sesame Street. This amused the audience (as noted, in all the wrong places) to no end. It also jettisoned any chance of the back story of his rocky relationship with Daschanel working. It just came across as painfully funny as they went through the motions. And key suspense moments, such as his working through solutions to the problem using grade school logic (literally, the grade school logic he taught in class), just became sit-comish.
Desperate for something - anything - with menace, the story randomly throws in the very crazy old woman using quick cut camera work and jolting soundtrack cues instead of delivering something that was actually scary. Or made sense. Or moved the story along. Or was not plain crap.
And the plants. If the story would have worked, perhaps many of the "scary" visual cues would have worked. But since this was a farce of a film, we were given plants gently blowing in the breeze and that was supposed to increased the adrenaline. In fact it only increased the laughs.
In fairness, there were two set pieces at the start which worked quite well visually: the park and the construction site. But he went to that well too often too quickly in following scenes, and the entire affair descended quickly into a steaming pile.