Duplex, a Danny Devito produced film, was not very good, but okay. The idea is worn and wasn't very good to begin with, but this movie had one element that served as it's saving grace: The acting was exceptional.
The movie chronicles the plight of Alex (Ben Stiller) and Nancy (Drew Berrymore). They are convinced by a mortgage broker to buy a spacious apartment, that he is willing to sell cheaply, but only for a limited time. They bite. There is only one problem. The tenant above them, a seemingly sweet old lady (Eileen Essell). Her pettiness and manipulation are grating on Alex and Nancy. They are spending all there time helping her do things, but Alex is writing a book which is due in a few days (Hint: If your manuscript is due in a few weeks, don't move!), and Nancy needs to keep up on her work as a graphic designer.
As can be assumed, the movie is fraught with annoyances, such as a police officer who thinks they are abusing her. This continues until Nancy gets fired and Alex needs to finish his second book pronto. He goes to the local Starbuck's, finishes it up, and comes home. Mrs. Connell needs him to help her with a rat. She predictably takes his laptop and throws it in the fire.
This is where the movie really loses it with me. It begins to get too predictable, and the movie begins to move inexorably towards an obvious conclusion, something heretofore I had high hopes for it avoiding. So, we are resigned to watching the excellent performance by the actors and trying to find some enjoyment from the ending.