The sight of Robert De Niro debasing himself in a moronic slapstick comedy barely even evokes a response anymore, so his presence in The War With Grandpa isn’t offensive, just depressing. Based on a 1984 novel by Robert Kimmel Smith, The War With Grandpa features De Niro in grumpy old man mode as Ed, an aging widower who is having trouble adjusting to life without his beloved wife. After an incident with a grocery store self-checkout machine (so hilarious when old people try to use technology!), Ed is stuck moving in with his daughter Sally (Uma Thurman) and her family.
The only space for Ed in the house is the room previously occupied by his preteen grandson Peter (Oakes Fegley), so Peter is forced to move into the attic, to spare his grandfather from having to climb multiple flights of stairs every day. This seems pretty reasonable, really, and the early part of the movie sets up only mild conflict within the family, establishing that Ed loves his grandkids (Peter has two sisters, one older and one younger) and they love their grandfather.
But that kind of gentle family comedy is not what the movie is going for, and soon Peter literally issues a declaration of war to his grandfather, and Ed goes along with it, leading to a series of pranks between the two that eventually causes injury, property destruction and family chaos. Peter comes off as an entitled little snot, and Ed doesn’t fare much better. Their conflict is petty and mean-spirited, and no amount of forced moments of family bonding can make up for the movie’s sour, unpleasant tone.
As usual with his work in mainstream comedies over the last two decades, De Niro barely bothers to put in an effort, while Fegley brings every ounce of sugar-rush kid energy he can muster, making for an uneven match between the two main characters. As Peter’s dad Arthur, Rob Riggle plays the same kind of well-meaning oaf he’s played multiple times before, and Thurman coasts through her role as the tut-tutting mom. At least Christopher Walken and Cheech Marin seem to be having fun as Ed’s buddies, who become accomplices in his war against Peter.
But the humor about old guys acting inappropriately doesn’t quite fit with the mostly kid-friendly tone. The subplots about Sally needing to be less judgmental of teenage daughter Mia (Laura Marano) and Arthur angling to earn Ed’s respect are far too mature for kids to take an interest (but far too hastily sketched to have any emotional resonance for adults). Also, there are multiple jokes about Arthur accidentally seeing Ed naked, and enough vaguely sexual references to make parents uneasy during family movie night.
Director Tim Hill’s filmography includes two SpongeBob SquarePants movies, a Garfield sequel, Alvin and the Chipmunks, and the Russell Brand Easter Bunny abomination Hop, so he has plenty of experience delivering loud, obnoxious humor for kids. He directs the movie like a mid-level sitcom, and it’s easy to hear where the canned laughter and “aww” moments would go. The life lessons for the characters are pretty flimsy, and the war mostly just runs out of steam at the end, rather than resulting in any lasting consequences. As in a real war, there are no winners—either among the characters, or in the audience.