Trash, but kinda fun. At least if you manage your expectations.
It's definitely not realistic, especially passengers' behavior (even considering one of the "plot twists"). Some plot points are underdeveloped, too. In fact, the whole plot is kind of meh. But I do not think this was filmed to delivery a super enticing story either way. I think the goal was to have a somewhat unhinged fighting movie.
Unfortunately, it's not that good at fights either. It definitely has its moments with sudden brutality, but the constant excessive camera shake was very distracting for me. It also does not go as unhinged as it could be, as if it's scared of something, and it could have used a bit more dark humor (and humor in general) instead of these "serious" moments.
I will completely forget it tomorrow, but as braindead movie to waste an evening - it's fine.
