Bringing in Mexican-born Cuarón to replace Chris Columbus for this third installment of the Potter franchise has, on the whole, proved a success. Though flawed, it's the most interesting movie of the three. The subtlety and sympathy Cuarón applied in his excellent Dickens and Frances Hodgson Burnett adaptations (Great Expectations and A Little Princess), he has brought to bear here, with a deeper characterisation of the now adolescent Harry (Radcliffe) and Hermione (Watson), and to a lesser extent their down to earth friend Ron. Where he can, Cuarón refracts the trio's battle with the crazed escaped prisoner Sirius Black (Oldman at his best), and the psychologically threatening aerial ghosts, the Dementors, through the subjective lens of teenage rebellion and its concomitant confusion of identity. Michael Seresin's camera stands further back from the action, and the prudent CGI and special effects (the noble, Pegasus-like Hippogriff; Grim, the omen of Death; the Shrieking Shack) aim to integrate more naturally into the kids' imaginative space. Will Potter fans accept this more reflective, angrier Harry? Gone are the celebratory tuck parties. Gone, too, dear old Richard Harris' paterfamilas, replaced by Gambon's less reassuring Dumbledore; with Thewlis' excellent Prof Lupin providing a new, more fractured father figure. Even the game of Quidditch takes place in the pelting rain, and there, as elsewhere, Cuarón resists the temptation to underline moments of danger, elation or triumph, preferring a more discreet use of soundscape and John Williams' score. Reflecting the darker tone of Rowling's third tome and characterised by its frosted, sombre, gargantuan Dark Forest, compared to its predecessors, this is a more wintry, thoughtful and rewarding movie.