As a film Serendipity is unenjoyable, one I could go the rest of my life never seeing this movie again and I'd be perfectly happy. However, I should say my opinion is likely biased; romantic comedies are not my preferred genre of film. As a consequence my experience with such films is limited, but from what little I have seen Serendipity would sit somewhat higher among the ranks for it’s occasional humor and wit.
In the movie Jonathan Trager, played by John Cusack, meets his “Dream Woman”, through a fortunate accident (called serendipity), who is a firm believer in fate or destiny and leaves whether or not she will continue to be with John up to chance. Several years later when both characters are about to be married (not to each other) they each go on a mad search for the other.
All in all the characters where flat, Sara and John are “good”, their spouses are subpar and their respective friends on their search for each other seem to serve no purpose other than to provide an opportunity for the main to characters to express their feelings.
The film isn’t entirely devoid of wit and humor, Eugene Levy, as a Bloomingdale's salesman, is humorous and entertaining. The closes misses and round about ways of finding of each other by the main characters are also amusing.
In conclusion Serendipity isn’t a great film, not even a good film but probably not a terrible one. If hard pressed, I might watch it again, if I was terribly bored. Maybe…