If you believe the previews or have seen the poster of an aggressively extended and bejeweled ring finger, then you might presume that “The Family Stone” is going to be a light-hearted romp of a comedy. Boy brings home uptight girl to meet his kooky and free-spirited family, amusing and embarrassing behavior follows, family and girl all learn important lessons about one another, then the movie ends on a wacky but upbeat note.

No, nope and not even.

There are embarrassments, humorous moments and lessons here as well as some physical gags, but the movie is a much more ambitious work that jumps all over the emotional spectrum before settling on quirky tear-jerker.

Meredith (Sarah Jessica Parker), as tightly wrapped as her hair and as annoying as the constant ringing of her cell phone, tries to hide her insecurities behind a brittle facade of confidence but ends up broadcasting every thought and perceived offense. That might be fine when she is in her element but going to the Stone home for Christmas as the girlfriend of beloved-son Everett Stone (Dermot Mulroney) makes her the square peg in this close-knit family circle. What Meredith doesn’t know is that Stone matriarch Sybil (Diane Keaton, who chomps through this role like it was cotton candy) is ill and that the interloper will make a handy punching-bag on which the family can take out their frustrations.

Stoner and truth-speaker Ben (Luke Owen), bitter Amy (Rachel McAdams), distracted mom Susannah (Elizabeth Reaser) and sunny, deaf Thad (Tyrone Giordano) round out the Stone siblings collected around the catalogue-perfect living room and mellowed by relaxed dad Kelly (Craig T. Nelson). When Meredith manages to offend nearly everyone in the liberal household, she calls in back-up in the form of lovely little sister Julie (Claire Danes who glows sufficiently to compensate for not having much in the way of a character to inhabit).

The strengths of this movie are top-notch performances, several more-than-a-bundle-of-quirks believable characters and plenty of space for the audience to have their own thoughts. Relative newcomer director Thomas Bezucha does a good job framing Diane Keaton’s scene-devouring energy and using an understated Luke Owen as the emotional anchor onscreen. However, these two cannot compensate for the movie’s lack of self-knowledge and forced sentimentality. Like the character of Meredith, the film’s bravado cannot mask a messy soul but should be given respect for showing up and sticking it out.

Parents should know that this movie has mature themes, including the illness of a family member, the projection of anger from something that causes pain to someone on the outside and the hypocrisy implicit in embracing acceptance but rejecting someone who does not think like you. A tender and committed interracial gay couple adopts, leading to discussions of race and sexual orientation that include some remarks interpreted as bigotry. Brothers tussle and try to hurt each other. An emotional character gets into a fender-bender off-screen. A character’s illness is the elephant in the room, about which nobody will speak. A character gets drunk and loses inhibitions, social drinking and references to pot smoking. There is brief profanity.

Families might wish to discuss the different ways the characters have of showing support and understanding, from Sybil’s discussions with Everett related to her mother’s ring to the scenes where Kelly and Sybil are alone. How is your family like — or not like — to the Stones and how would you react to a newcomer to the family who seemed different?

Families looking for more movies that highlight messy familial tensions around holidays might wish to watch the thoughtful Pieces of April, What’s Cooking or Home for the Holidays. Those who wish to see Diane Keaton demonstrating her comedic chops should watch Something’s Gotta Give or Annie Hall.

Thanks to guest critic AME.