In his first starring role minus his longtime partner Peter Cook, Dudley Moore plays a 29-year-old who goes through an identity crisis when approaching the "three-oh" mark. He wants to be a successful Broadway composer before reaching 30 and also wants to be happily married. Unfortunately, he's so busy as a night-club musician that he hasn't any time to realize his goals. Enter sexy Suzy Kendall (Mrs. Moore at the time), who inspires Dudley to reinvigorate his quest for success and connubial bliss. 30 Is a Dangerous Age, Cynthia delivers a satisfactory quota of laughs; its only drawback is its heavy reliance upon "mod" '60s camera trickery.
~ Hal Erickson, All Movie Guide