Jeff Garlin, charming, never maudlin.
Sarah Silverman is her thoroughly attractive self. As the lead says, what can he do, he likes them young and insane. When she's uncomfortably over-the-top, it's the character's fault, not the actor's.
Bonnie Hunt, what can I say, she is never less than a treat with a cherry on top.
The main thing I'd add to the excellent reviews by Ed Uyeshima and CountryJim: pay close attention. The last three minutes say an awful lot. The big twist in the middle left me feeling abandoned. The denouement at the end tied me back in.