The relaxing opening music and reassuring title suggest this will be a warm fuzzy feelgood movie with a nice star turn from Will Smith. The switch to grainy film and self-consciously natural performances start to eat away at such assumptions. Will Smith plays the rags-to-riches father, but wades through heartbreaking poverty before he can climb the ladder to apprentice stockbroker, all the time bonding and maintaining good spirits with his son whom he loves dearly.

The title, from the Declaration of Independence, affirms the American Dream. We might wish that Will Smith, for all his acting skill (his performance is the best thing about the film) could expedite it a little more - two hours, when the end is a foregone conclusion, feels like labouring the point. The clunky story comes to rely overmuch on the undoubted chemistry between father and son (played by Will Smith's real life son) and one of the best performances of Smith's career. Its main achievement is its heartfelt depiction of fatherhood.

It might well be 'inspired by a real story', as the credits claim, but the broken-marriage, salesman-down-on-his-luck, yet fighting-through-to-a-better-day, is formulaic in the extreme. Smith sells bone density scanners - an item he has bought many of in the hope of making a profit. Although he has the ability to solve a Rubik cube in a short taxi ride, he still manages to lose his scanners repeatedly, providing repetitious sub-plots as he struggles to retrieve them.

One of the best scenes is when father and son, homeless, are stranded in a subway station. Dad pretends that the bone density scanner is a time machine as a game to distract the young lad from the seriousness of their situation. They sleep in a disused latrine, perfectly dressed - Smith has to attend broker induction classes in the morning.

The Pursuit of Happiness holds a nice idea, but one that could be told in a half hour TV slot. Its suggestion that happiness is equivalent to money grates somewhat on the non-American ear, especially considering the film's relentlessly didactic tone. A great vehicle for Smith to show his talents as a serious actor, but not a movie that in any other way comes up to the standards he admirably sets.