To Rome with Love (12A) ** About Elly (12A) ****

Three's a crowd: Alessandro Tiberi, Roberto Della Casa and Penelope Cruz in 'To Rome with Love'

Woody Allen plays a version of himself in To Rome with Love, an avant-garde opera director who's chafing at retirement but looking all of his 76 years. Allen's solution is to pack his new film with virile young men and luscious young women, to uphold the vitality of youth he can no longer have for himself. There is probably no other director with a run of duds like his who could keep assembling such strong casts. It is as though these actors will accept any part, however paltry or underwritten, just so that they can say they worked for Woody.

This latest isn't terrible, it's just slipshod and careless, like a first draft he hasn't bothered to work on and tighten up. It's an airy ensemble in which Rome itself takes the leading role: at one point the camera does a 360º spin around the Piazza del Popolo and seems to swoon at the beauty of it all. One vignette follows close on another. Allen and his wife (Judy Davis) are visiting their daughter and her Italian beau, a lefty lawyer with a father who's a mortician: "What does the mother do – run a leper colony?" Alec Baldwin plays an architect who bumps into a young expat (Jesse Eisenberg) and tries to steer him clear of the alluringly neurotic actress (Ellen Page) who would steal him from his nice girlfriend (Greta Gerwig). A newlywed couple (Alessandro Tiberi and Alessandra Mastronardi) arrive in Rome and are instantly plunged into temptation, she by a famous Italian actor, he by a call girl (Penelope Cruz, in an eye-catching raspberry minidress). A Pooterish family man (Roberto Benigni) steps out of his apartment to find himself an overnight celebrity, pursued by the paps and squired to movie premieres with dolly birds on his arm.

Allen is riffing on some favourite themes – romantic regret, the vicissitudes of attraction, chance meetings, the vacuous nature of celebrity – and gussying them up with light, fantastical twists. The quality of the writing is extremely variable. Baldwin, who calls his dissatisfied middle-age "Ozymandias melancholia", nicely plays conscience to a kid, trying to save him from his mistakes. And Allen himself, looking frail, still lands a good punchline: "I was never a communist – I couldn't share a bathroom." But the belated discovery of an operatic talent (Fabio Armiliato) who can only sing in the shower, the misunderstandings and the farcical bedroom shenanigans are desperately overstretched. As the sap who's had celebrity thrust upon him, Benigni is wonderfully bewildered at first –he's never enjoyed such attention, anywhere. Once the spell is broken, however, the film hangs him out to dry in a long, unfunny scene of public protestation.

How Allen will bring these stories together is a question that nags away. The answer: he doesn't. The characters don't intersect with or comment on one another, and there's nothing, apart from the city, to unite them. With his creative spark all but extinguished, it's only Allen's reluctance to retire that keeps him afloat. He won a great deal of affection last year for Midnight in Paris, an elegant jeu d'esprit that leaned heavily on past glories but got through on the charm of its conceit and performances. This one will not rank so high, even among the slim pickings of late-period Allen. "With age comes wisdom", someone remarks. "With age comes exhaustion", their interlocutor replies, which is most definitely Woody in 2012 – exhausted, but damned if he's giving up the ghost.

About Elly is the film Asghar Farhadi made before his award-winning A Separation (2011), and presents another moral drama of remorse and recrimination that haunts you long before its close. Once again, the patriarchal system of authority in his native Iran broods over the unfolding. The opening half-hour wrong-foots us entirely as a group of thirtysomething college friends and their kids take a jolly three-day trip to the coast. Installed in a roomy but dilapidated beach house, they horse around, chew the fat, play party games. Vivacious group leader Sepideh (Golshifteh Farahani) has brought along a guest, Elly (Taraneh Alidoosti), a shy but amenable young woman who teaches their daughter. Sepideh has an ulterior motive: she wants to matchmake Elly with her friend Ahmad (Shahab Hosseini) who's just returned from Germany following a painful divorce. As he explains, in a phrase that will reverberate for everyone involved: "A bitter ending is better than an endless bitterness."

The subtlety with which Farhadi sets this up will come to seem all the more admirable in the light of what ensues. Unguarded remarks, stifled giggles and casual requests will all be picked over as disaster arrives out of nowhere. Elly disappears, and once the holidaymakers realise what has happened the very idea of her presence among them becomes a source of painful inquiry and gathering panic. (Nobody actually knows her surname to tell the police). Every step they take to get themselves out of the hole only serves to wedge them in deeper. Sepideh, whose friendly manipulation ensured Elly's somewhat reluctant compliance in the first place, is utterly traumatised by guilt; Golshifteh Farahani's remarkable performance, her eyes dark from fatigue and weeping, seems to age the woman before our eyes. Shahab Hosseini as Ahmad is also compelling as the other half of Sepideh's Emma-like meddling.

What the film expertly develops is a sense of how these middle-class friends have unwittingly implicated themselves in something that now assumes the status of a religious offence. Yet it also poses a question about Elly, whose own tangled past may have driven her to take a more active role in the tragedy than we could have guessed. On the level of plot alone About Elly is superbly handled; each scene of revelation or of withholding is key to a later development. Alongside A Separation it will only enhance Asghar Farhadi's reputation as a filmmaker of technical brilliance and serious moral inquiry.