Cameron Crowe has always had a propensity for cuteness, with a feelgood agenda built into his DNA, complete with infinite playlist.

He may acknowledge life's cynicism and woes, but the aim is always to leave his audience feeling upbeat. When it works, as in Jerry Maguire and Almost Famous, one appreciates the shameless escapism; when it doesn't, as in Elizabethtown, the jolly offensive becomes extremely tiresome.

At least with We Bought A Zoo, Crowe has the excuse of it being his first family film. It's based on a true story and accompanying book by Benjamin Mee, a British journalist who moved his extended family, including his elderly mother and dying wife, into a struggling Devon zoo, and found that the experience of bringing the place back to life created a diversion from grief when his wife succumbed to her illness.

Crowe has moved the action to California, streamlined the family and presented his hero, from the outset, as a single dad. Played by Matt Damon, Mee is a charming thrill-seeker, the sort of reporter who will throw himself into any situation, however dangerous, with engaging naiveté and a desire to find the human idiosyncrasy in the story. But six months after his wife's death, Mee is at a loss. While seven-year-old Rose (Maggie Elizabeth Jones) is young enough to enjoy a sort of happy obliviousness, both Mee and his teenage son Dylan (Colin Ford) are struggling to adjust. The boy's awkward way of expressing his grief comes to a head when he is expelled from school, prompting Mee to decide that the best way forward is to relocate.

Resigning from his paper, Mee goes house-hunting. When he sees a large, ramshackle house, set amid beautiful countryside, he immediately falls in love with it; when he learns that the house comes with a zoo, which needs urgent attention, he buys it anyway. Mee and his in-situ staff – led by Scarlett Johansson's serious and dedicated head zookeeper, Kelly – have a few months to renovate the zoo and gain a new licence before a summer opening; in the meantime, Mee must juggle his new role as zoo proprietor with the rehabilitation of his family.

The film is most assured as it puts its pieces into play. The excellent Damon convincingly engages us with a character whose default position throughout his life has been gung-ho, and who can't quite let go of his reckless instinct, even now. His sensible elder brother (Thomas Hayden Church) implores him to "travel the stages of grief, but just stop before zebras get involved". Yet Mee is about to enter the lion's den, literally and metaphorically.

To his credit, Crowe doesn't pay attention to genre clichés. In almost any other film, for example, the relationship between Mee and Kelly would open in conflict, warming towards a gushy romance; not so here, as Kelly's first concern is her animals, and Mee's the still-fresh memory of his wife. But Crowe has bad habits of his own. A former music journalist, he seems to add scenes just so he can feature another favourite track from his iTunes playlist – leading to huge tracts of unnecessary material and galling whimsy. However, as clumsy and relentless as this is – more of an extended love-in than a film – its charm just about wins the day.