Olivier Assayas is a difficult director to pin down. The son of a screenwriter and a former critic on Cahiers du Cinéma, he combines a respect for film art with a passion for mainstream genres. Consequently, his output has alternated between intense, intelligent dramas and quirky curios that have occasionally veered off into erotic eccentricity. But he's on restrained and perceptive form with Summer Hours, a paean to the Musée d'Orsay on its 20th anniversary that typifies Assayas's habit of littering his pictures with homages to favourite film-makers.

The dismal sense that globalisation has unleashed an irreversible philistinism pervades this melancholic domestic drama that proudly exhibits its debts to Louis Malle and Eric Rohmer. It's clear at Edith Scob's 75th birthday party that only son Charles Berling genuinely cares for the family's artistic heritage and, on her passing, younger, jet-setting siblings Juliette Binoche and Jérémier Renier agree to the sale of her country home and its treasured collections with an alacrity born out of callous self-obsession. However, Assayas is too aware that times and temperaments change to allow Berling's sentiment to taint proceedings with tasteless nostalgia. Moreover, he also eschews easy characterisation and validates Jean Renoir's maxim that everyone has their reasons by revealing a softer side to Binoche and exposing Berling's inadequacies as a father.

Deftly played to capture the fissures in family life, this may lack depth. But its observations on human transience are deeply moving and Eric Gautier's images of the country cottage and its atmospheric interiors are sublime.

A very different rustic dystopia emerges in Puffball. Nicolas Roeg's first cinematic feature in 12 years shows flashes of the visual ingenuity that made the onetime cinematographer an arthouse darling in the 1970s. However, they're dismayingly rare and, consequently, this idiosyncratic adaptation of Fay Weldon's 1980 novel rapidly descends into a hysterical chaos that's exacerbated by the skewed storyline, the overwrought performances and a self-conscious reliance on sex, clumsy symbolism and gimmicky 'womb cam' imagery.

Miranda Richardson and Rita Tushingham are particularly guilty of excess, as they engage in an Irish variation on voodoo to punish pregnant architect Kelly Reilly for 'stealing' the child they crave to replace a son killed long ago in a fire. But it's Donald Sutherland's superfluous cameo, as Reilly's Nordic boss, that best sums up the pretentious preposterousness of this muddled, misfiring mess.

The script is equally troublesome in Johnnie To and Wai Ka-fai's Mad Detective, with the disappearance of rogue cop Lam Ka-tung's partner and the use of his gun in a series of murderous robberies being all-too-neatly solved by the late introduction of a previously unseen collaborator. Moreover, the co-directors never quite solve the problem of how to depict the multiple personalities that eccentric sleuth Lau Ching-wan recognises within Lam's damaged psyche.

But while fans of To's rigorously steely gangster movies may be a little bemused by this undisciplined romp, it remains a consistently engaging comedy thriller that's stuffed with imaginative set-pieces, including the opening montage in which Lau demonstrates his unorthodox crime-solving methods to new assistant Andy On and a bizarre restaurant encounter involving On (who, five years later, has enlisted the disgraced Lau to help crack the case), his inspector girlfriend and Lau's imaginary wife.