Keeping in mind this is an independent film, I highly recommend it as a quirkily fun watch.
Jack is your stereotypical NY businessman, stuck in his groove, far from happy but 'satisfied' with the status quo. Jill is the stereotypical free spirit who crosses paths with him while lost in the city (trying to find a street using a subway map). Jack is intrigued by Jill, doesn't like the idea of her living in a shelter with no contacts in the city, so he invites her home to use his spare bedroom. Jill spices up his life, brings out his smile, and even his best friend/coworker notices a change in Jack for the better. But Jill has a penchant for disappearing for stretches of time, and this really bothers Jack. Their manifesto says "Be Honest"... but Jill's hiding the fact that her lungs are giving out on her via Cystic Fibrosis and she has to check into the hospital for 'tune-ups' when things get bad for her. When Jack finds out the truth, will he ditch her, or realize that life is short, and you grab on and live it with those you love, waging war on the ugly bits. The movie is very "Sweet November" with a more charming hero and more child-like heroine.
I know the plot sounds like a tearjerker, but this is hugely light-hearted for a drama (from 5000 'Stupid' stickers being thrown off a building, the off-the-wall best friend who flings ice cream and does the robot while singing poetry, and a wrestling 'fight' between two business men on the company's roof... to philosophical conversations with pigeons). Surprisingly, for a dying heroine movie, this has a wonderfully happy ending.