Sundance 2014: Infinitely Polar Bear reaction

More than any other festival, Sundance has acted as the launchpad for some of the most interesting, cool and uniquely voiced directors of modern cinema.

This year, it could just be writer and first time director Maya Forbes who kickstarts her major movie career, thanks to the sweet, warm, funny and nowhere-near-as-annoying-as-the-title-may-suggest dramedy, Infinitely Polar Bear .

Having already written 2009's under-appreciated Monsters vs Aliens , Diary of a Wimpy Kid 3 , and a host of episodes of The Larry Sanders Show , she's certainly no stranger to Hollywood, but Infinitely Polar Bear marks her directorial debut, and it's an impressive introduction.

Based on the writer-director's own life story, it follows one family's struggle to function in the wake of the father's diagnosis with manic depression.

After a full-on breakdown and subsequent treatment, Cam (Mark Ruffalo) returns to a family in which his lovingly supportive but emotionally stretched wife Maggie (Zoe Saldana) struggles to make ends meet, while bringing up her fiery, clever and dynamic daughters.

With Cam unable to hold down a job (or his own mood swings), she's forced to up sticks to New York and study for her business degree, thus leaving Cam in charge of the girls. Chaos, calamity and chuckles inevitably reign.

While the tale is in itself fascinating, and Forbes' direction vibrant and warm-hearted, it's the casting that helps the movie soar.

Imogene Wolodarsky and Ashley Aufderheide prove instantly adorable and endlessly amusing as the argumentative, impassioned and increasingly exasperated pre-teen daughters, and Ruffalo is as fun as he is infuriating as the familial tornado responsible for both adrenalising and dismantling the status quo - but it's Saldana who really shines, offering dramatic shades hereto unseen as the matriarch torn between her children, her husband and her work.

Sure, every so often Ruffalo tips a little too far into manic quirk overdrive, and those looking for a serious and brutal look at living with a loved one suffering from manic depression will find more than a whiff of the Silver Linings Playbook school of life lessons. But then Infinitely Polar Bear was never meant to be a somber, dour and emotionally destructive look at mental disability.

Forbes actively sought to create a warm, affectionate ode to family life, no matter how dysfunctional, and in that she's certainly succeeded.

Appropriately enough, Infinitely Polar Bea r is likely to polarise - but for those looking for a feel-good, low-key family drama, this could be the surprise of Sundance.