The addition of Brian Bonsall as the preschool-aged Andy injects new life into the show, setting up Family Ties: The Fifth Season as one of the series' most memorable. Andy's screentime is understandably limited, but his ability to interact with the rest of the crew gives the writers new territory to explore with the Keaton's particular family dynamic. In one episode, each of the Keaton kids try to mold Andy into their own particular vision of what a little brother should be, ranging from Mallory's (Justine Bateman) young, leather-clad rocker to a Mini-me version of Alex (Michael J. Fox).
Andy also provides a much-needed distraction to Alex, who is faced with what is probably the roughest year of his life. Not only does he have to deal with breaking up with is girlfriend, Ellen (Tracy Pollan), but he loses one of his best friends in what is easily the season's most powerful episode. In "A, My Name is Alex", Alex backs out of a commitment he made with his friend Greg. Greg is later killed in a car accident, sending Alex into a downward spiral. The second half of the two-part episode is particularly memorable since it is mostly Michael J. Fox on a dark stage while short episodes from his life play in the background.
While Alex (and his relationship with Andy) is still a centerpiece in most episodes, the other Keaton kids manage to get in on the act. Mallory takes on the daunting task of tutoring her boyfriend, Nick, and Jennifer (Tina Yothers) joins a band. There are also a few noteworthy guest appearances by Will Wheaton and Christina Applegate.
The addition of a new cast member doesn't earn the same respect as Michael Gross's beard (one of the few parts of the show to earn a Special Feature), though there's a fun gag reel that includes bloopers from rehearsals.
It's hard to not recommend Family Ties: The Fifth Season. It is one of the series' best and incredibly fun.