Oblique, arcane and infuriatingly sluggish, even by Tarkovsky’s standards (makes Andrei Rublyov look like Moulin Rouge), Nostalgia is the litmus test for arthouse cinephiles. The ‘story’ of a Russian poet locked in existential agony while researching an obscure 18th-century composer is brimful of breathtaking tableaux, portentous dialogue and primal symbolism (flickering flame as human soul). But is it enough?