The story evolves around the beaten to death horse "nerd guy gets ditched by dream girl, meets other nerd girl, dream girl wants to get back and nerd guy gets in conflict of which of them he should choose".
Naturally this is not much to fill a full length movie with, so you better got some brilliant cast to make up for this shortcoming. Unfortunately the cast of the movie is average at best, with a quite bland Jennifer Aniston and a mediocre Ben Stiller in the leading parts. Also i never had the impression of some chemistry between them, which never is a good sign for a romantic comedy.
The comedic value of this movie is low, with no memorable scenes whatsoever. Most of the gags are situational, which unfortunately are not well executed, but match the story in all it's irrelevance perfectly.
All in all it is a boring but quite family-safe romantic comedy, which doesn't rely too much on fart-jokes and vulgarity like other of Stiller's work.