There are more factors than the plot alone. There's the soundtrack, acting, film work, actors themselves, etc... I can name countless movies that don't have the most convincing subject matter but are great movies, and vice versa; some movies have interesting plots but the way they carried it out was absolutely horrible (think: Happy Death Day).
What I mean by this is sometimes movies are judged by the subject that the film is addressing, particularly if it involves a social issue. In some cases, the subject matter is of importance, but the film itself is not satisfying. Prisoners (2013) is a good example from my perspective; despite the favorable reviews it received, I thought it was terrible.