One of the (many) disadvantages of getting old is that plot points that used to look fresh and new start to look old and tired. In this case the frequently repeated trope is "dying relative causes dysfunctional family gathering and speaks the truth." You couldn't ask to do it with a better set of players: Billy Connolly is the father with terminal cancer, David Tennant is the son who just had an affair, and Rosamund Pike is the ex-wife who's faking still being with him for the father. They have three kids (Emilia Jones, Bobby Smalldridge, Harriet Turnbull) who're all surprisingly decent actors. But the authors seem to think they have a free license to have the kids say anything that's humorous. This works up to a point (they're kids), but goes beyond believability after a while. The movie nevertheless moves relatively smoothly between black farce and pathos and manages to be a fairly enjoyable take on an oft-used idea.