question

The use of the verb "to compell" with regard to an artistic endeavor, such as a motion picture, means one is drawn into the artistic experience, that one enjoys the experience more fully. So, a "compelling plot twist" would mean a change (a twist) in the plot (the story upon which the motion picture is built) which gives the viewer a more enjoyable experience, a change in the plot which draws the viewer more fully into the experience of the motion picture.

I feel that the sentence is badly constructed however. "Despite compelling plot twists, this film is hard to watch." One would assume that the "compelling plot twists," the unexpected changes in the story, would be the very reason why the motion picture is hard to watch. I suggest that whoever wrote this sentence was more impressed with their command of the language than is warranted by the obscure sentence she or he has produced.