“Something's Gotta Give” is an enjoyable movie, though the comedy is very sparse and it's more of a light drama than a “romantic comedy”. The last 15–20 minutes fails to live up to the rest of the film which is engaging, likeable and occasionally quite funny.
Keanu Reeves seems a bit out of place but makes an admirable effort in a forcedly written role. Jack Nicholson is his usual self, which is fine but he's nothing special. The main reason to watch this movie is Diane Keaton. Though it's similar to some of her other performances in similar films, her unpredictable and endearing personality makes her completely believable in the role of an older woman attractive to men of varying ages. She's also the funniest of the actors in the film and even stands out in the dramatic scenes. In my opinion she deserved her Oscar nomination in a year full of outstanding actresses, and of course her Golden Globe for Best Actress in a Comedy.
If it wasn't for the lacking last act of the film, I would probably give it four stars, but as it is Diane Keaton is enough to warrant three.