If you can forgive the fact that the producers of I.Q. took some liberties with some history and scientific fact, you are most likely going to enjoy the movie. The story is set during a time Albert Einstein (Walter Matthau), Kurt Gödel (Lou Jacobi), and Boris Podolsky (Gene Saks) are alive and busy arguing about the absolute nature of time and determinism (one would've thought Bohr would've fitted better here). The main plot is about a car-mechanic, Ed Walters (Tim Robbins), who falls for Einstein's insecure niece Catherine Boyd (Meg Ryan), when she visits him in a auto-shop. Einstein realises this and think Walters a better match for Boyd than her fiance. So along with his colleagues, he fabricates a scenario where it appears as though Walters is responsible for inventing fusion-powered nuclear spacecraft (which we all know is not possible, right?). This indubitably impresses Boyd until the whole thing starts to fall apart.
The plot is reasonably original, grounded, and funny. While Meg Ryan did a great job, I thought the acting could've been better by some of the other characters. There really seems to be no reason why someone often goes "time doesn't exist" during the course of the movie, but the interplay of determinism, as depicted by classical physics, and non-determinism, as depicted by Quantum Mechanics, fits in well with how the group of genuises try to initiate chemistry between Boyd and Walters.