On a balmy evening in Milan, where the first scents of cherry blossom wafted through the breeze, it was in theory a short perceptual leap that would transport us to the sultry world of Sevillian signorinas, strapping toreros and searing love affairs in Bizet's Carmen. There was anticipation in the air as queues stretched way back for a sold out performance. But a flat atmosphere soon fell in the auditorium itself, with lacklustre singing and confused staging to blame for that. Ultimately, it was a dispirited audience that filtered into the by now much cooler Milanese night.

This is the year of Milan's Expo - the international Summer exhibition on everyone's lips - for which La Scala have extended their season and pulled some old productions out of the wardrobe. Emma Dante's Carmen received a famously mixed reception at 2009's season-opening performance from press and public alike. Barenboim assured it would become "a legend production", whilst traditionalist opera director Franco Zeffirelli claimed that it had caused him to see the devil.

This year's version remains largely intact, though the original star-studded cast has received an overhaul. There was often a lack of chemistry between tonight's leading roles this time around. Elīna Garanča's blonde Carmen possesses an innocent streak, and her cheery "Habanera" lacked the necessary sass to get our pulses racing. José Cura's Don José is world-weary and seemingly old enough to be Carmen's father - impassible and often immobile, he hardly flinched when Micaëla relayed news from his dying mother, sweetly conveyed by Elena Mosuc as this was. Such a low voltage rapport between the main characters made it difficult to buy into the plot's tragic developments or the various directorial quirks. In a reversal to conventional practice, Carmen rather than José plunged the dagger into her heart at the work's climax, which was a somewhat implausible feature when there had been so little in the way of a dramatic buildup.

But in spite of these weaknesses, there were moments where the characters' relationships started to kindle. Carmen ensnared her captor José with a hazy "Tra la la", entangling him in the suspended ropes that bound her arms, and the tension bubbled in a candelabra littered Lillia Pastia's, with José tormented and Carmen burning with resentment at his refusal to desert the army. There is by now some wobble to Cura's voice, but he is capable of shifting cleanly through the gears to find an emotive range.

Massimo Zanetti, a dapper silver fox of a conductor, overflowed with energy, and we might have wanted him to steal through the texture more often to provide some oomph. The prelude to Act III had utter poise, whilst that to Act IV brimmed with joie de vivre and all the zest of Seville oranges: smouldering strings, lippy brass and rapping tambourine. And there were also heart-warming contributions from gypsy swashbucklers Frasquita and Mercédès, charmingly conveyed by Hanna Hipp and Sofia Mchedlishvili respectively. There is impressive depth and sheen to Mchedlishvili's voice who, like her fast-rising compatriot Anita Rachvelishvili, is a product of the La Scala Academy.

A much bigger problem in this production than casting or individual performances was posed by the direction and scenography. Dante shares with Zeffirelli his penchant for buzzing, bustling sets, which was easy on the eye in the case of Act I's heaving piazza with marching children, trinket flashing gypsies and a woman giving birth. But incongruities between the sets cause disorientation when we switch to a geometric blankness for Act III's mountains, or to Act II's Lillia Pastia's Inn in an underground lair, borrowed from a James Bond villain perhaps, where a slowly descending dumb waiter didn't allow Escamillo the most imposing entry (sung with bravado nevertheless by a tightly-clad Vito Priante). Without grounding in time, place or a coherent aesthetic, the narrative is left to flap helplessly in the wind.

In particular, Dante has the tendency to clog the drama with cloying symbolism. Religious imagery abounds, for example with a hearse crossing the stage to spell out Carmen's imminent death from the off. When factory girls dressed as nuns disrobe to nightdresses before frolicking in a steam-filled fountain, we are unsure whether we are supposed to feel aroused or amused. Far from sharpening our focus, the symbolism tends towards the obscure, and it is often gratuitously nauseating, so that watching bloodied factory girls kicked into the air by raving soldiers made for an uncomfortable sitting. It was surely no coincidence that moments of dramatic clarity coincided with respite in the stream of allegory.

An ultimately disappointing performance, then, with glimmers of musical distinction. Dante's Carmen returns to La Scala in June with Rachvelishvili in the title role (surely the hottest Carmen around) and the honey-toned Francesco Meli as José. If any cast can overcome the production's faults, it could be this one.