The simple premise of this suburban comedy — about a group of dads who form a neighborhood watch group to patrol their block, but soon discover an extraterrestrial menace threat far beyond their control — feels like a lazy opportunity for Ben Stiller, Vince Vaughn and Jonah Hill to hang out and crack wise on the studio dime.   

If ever there was need for an example of the whole not adding up to the sum of its parts, then let 'Couples Retreat' hereby stand as Exhibit A. The movie assembles four couples in relationships in various stages of duress and quickly trots them off to an island paradise where all of their problems will be solved — not before they go out of their ways to make things much worse, of course. Grade: D.