This is a wonderful film. It has an irresistible plot of two attractive professors (he's got the looks, she's got the witty personality) trying to conduct a platonic marriage having found a genuine liking and affection for one another. Jeff Bridges is perfectly cast as the helplessly sexy, rumpled academic who after being unlucky in lust seeks a passionless and thus more 'solid' marriage. Barbara Streisand is lovely as a brilliant, frumpy, hopeless romantic. Between his helpless sexiness and her hopeless romantic-ness you know you are set for an emotional equivalent of a 'rags-to-riches' rollercoaster, all delivered with plenty of laughs as well as insightful (even tearful) moments.
The supporting cast, notably George Segal and Lauren Becall is generous in making the leads look even better whilst providing great comedy and solid emotional backdrops to the story as well.
The climax provides an emotional crescendo (dramatically as well as musically!). If you like rom-coms with a bit of thought thrown in then treat yourself, buy this film.