I believe that what makes the film version of Wit so good is the inspired collaboration between Emma Thompson (who stars as the main character) and Mike Nichols (who directs the film). They co-wrote the script together and bring to bear a collective experience from both stage and film. These are two individuals who thoroughly know what works and what doesn't in both formats.
And there is a lot that works about Wit. From the smart screenplay adaptation to the acting to the carefully planned moments in which the fourth wall is broken. There isn't a wrong move made in the entire film.
The story is about a literature professor named Vivian Bearing, who learns that she is in the last stages of ovarian cancer and is enlisted in an aggressive, but experimental treatment program as part of a cancer study. In an effort to retain some sense of control and perhaps her humanity, Vivian begins chronicling her experiences with the treatment, resulting in periodic monologues describing her circumstances with a sense of irony, humor, heartbreak, and yes...wit.
As an academic, Vivian is able to bring a cold, analytical eye to the situation and breakdown in some detail the systematic monotony of being chronically ill. However, she is also a woman facing her own mortality in a series of very painful steps. The script, brought to life by Thompson's performance, doesn't shy away from the real fear that Vivian is feeling as well as the regret she experiences in looking back over her life, a life she dedicated to becoming the leading authority on the holy sonnets of John Donne, often at the expense of human empathy and connection.
When you watch, look for the scenes between Vivian and Nurse Susie (played by the wonderful Audra McDonald), for here is where viewers will find the true message about human compassion and kindness. In small, simple gestures, Nurse Susie expresses more understanding about the human condition than anything the more learned characters espouse, including Vivian.
The film originally aired on HBO and never received a theatrical release, which is just as well since I think the big studios would have had a hard time knowing how to promote this film. Below is the only trailer I could find; it was one that aired on HBO at the time.