Joan Rivers is a very funny person.
If you agree, then Joan Rivers: A Piece of Work, which opens today at the Landmark Magnolia and Angelika Plano, will prove to be a revealing and honest accounting of a year spent in her company. The documentary, directed by Ricki Stern and Anne Sundberg, sticks very closely to Rivers throughout its running time. Interviews with others are kept to an absolute minimum, and almost all are with members of her camp. What results is a claustrophobic portrait, painted from one angle, that, nevertheless, is compelling to watch.