The first critics to review Harry Potter and the Prisoner of Azkaban are mostly spellbound by the young wizard's third adventure. Here is a sample of what they have said so far:
Daniel Radcliffe is back as teenage wizard Harry Potter
The Daily Telegraph
The Prisoner of Azkaban is far more visually striking than its predecessors. Finally, here is a film that does justice to Rowling's soaring imagination.
When the action shifts to Hogwarts, Cuaron is like a kid let loose in a toy store. He clearly relishes its cloisters, its nooks and arcades, its giddily ascending staircases, and he allows his camera to swoop and pan and zoom as if at will.
The virtue of a director with a fresh pair of eyes is evident. When Cuaron was appointed, a few eyebrows were raised. He is, after all, best known for the splendidly raunchy Mexican coming-of-age film Y Tu Mama Tambien.
This is the best Harry Potter film to date, and its moral seems clear - hire other directors who can add spice, grit and quirkiness to Rowling's stories. Cuaron clearly wanted to make us feel we'd experienced a proper movie. He succeeded.
I had heard talk that this Potter movie was a lot darker than the others.
There's no doubt this is true - the Dementors, for example, make the man-eating spiders of Harry Potter 2 seem like a bunch of friendly daddy long legs.
Much of the movie focuses on Harry "growing up" and confronting issues in his life: the death of his parents, the Dementors, his future as a truly-gifted wizard (something touched on in the first two but actually put into practice here).
However, this theme is effortlessly sewn in with the familiar elements of Harry Potter we know and love: the awfulness of the Dursleys, the magic of Hogwarts, the odious Malfoy's consistent comeuppance, the irrepressible imagination of author JK Rowling.
Cuaron's appointment to this franchise is the most inspired Hollywood gamble of the year. He is not a proven director of blockbusters or indeed sequels, but any misgivings about his ability to bring home the lucrative bacon evaporate frame by lavish frame.
The change of mood and purpose is palpable. Hogwarts is a far richer and darker retreat than Chris Columbus's gothic fairground. The portraits are more animated; the spooks more sardonic; the rivalries more poisonous.
The camera work is a sensual feast. Cuaron favours wide-angle lenses, and you could spend weeks drooling over the artwork in a single scene. If there's a weakness to his film, it lies in the fiendishly ornate plot and the director's blind faith in our ability to follow it.
The difficulty of distinguishing friend from foe is the film's potent theme. But it becomes a maddening handicap when the story starts galloping around the final hairpin bends like a Hitchcock thriller.
New director Alfonso Cuaron's bold plunge into the world of wizardry's darker side has produced an absorbing film with a very different flavour from Harry's first two big-screen adventures.
Daniel Radcliffe's famous bespectacled features have become synonymous with the engaging character whom author JK Rowling has turned into a global phenomenon.
The Prisoner Of Azkaban also features Harry's trusty companions, know-all Hermione (Emma Watson) and Ron, hilariously played by the excellent Rupert Grint. In this film, the 13-year-old Harry is more cynical and more confused as he faces up to the grim fact that his true fears are within him.
Unlike the Disney-style sets of the previous two films, this is an icy, black, brutal world where it never stops raining. Most terrifying of all are the Dementors - deathly ghost guards who feed on hidden fears and extract all joy from your soul.
Ain't It Cool News, US film website
Combining the magic of the really real, the nearly real and power of pixels, Cuaron brings to life JK Rowling's Harry Potter in a way we have yet to see fully before.
Daniel Radcliffe is fantastic in this edition. Rupert Grint's (Weasley) defuses a scene effortlessly and that is true magic.
Every now and again you see an actress so young and gifted that she makes one take pause. Emma Watson (Hermione) is a miniature adolescent Grace Kelly.
Alfonso Cuaron he startled me throughout the film with cinematic devices, emotional directions and stylistic flourishes.
Cuaron really has such a light touch to this story, in the end it all feels so easy, so elegant and so effortless. He understands magic more purely than anyone I'm watching make films today.
Harry Potter and The Prisoner of Azkaban turns out to be entirely chaste - implausibly chaste; given what else goes on in Hogwarts you'd think the magic of romance would tickle at least one or two of these teenage wizards. So far we haven't seen so much as a peck on the cheek.
Cuaron does, however, import something different into a series whose blandness under Columbus had become crowd-pleasing to the point of suffocation.
He and his cinematographer Michael Seresin have darkened the Potter palette to a medley of blue-blacks, gunmetals and sickly greens, and fitted out the Gothic interiors with a disquieting touch of noir: mirrors, shadows and flickering lights are significantly featured.
The allure that production designer Stuart Craig creates around Hogwarts and its environs is thrillingly sinister, and certain elements of its funhouse gaudiness are ingenious, such as old portraits inside, which the sitters fuss and complain, or, in the case of the Fat Lady (Dawn French), are abducted from one picture to another.
Harry Potter and the Prisoner of Azkaban is... literally darker than the first two bright, clean movies that Chris Columbus delivered: a touch muddier, a hint grainier in its look.
And to add to the general air of disquiet, there seems to be - unless I am imagining this - a silent, fleeting cameo at the very beginning by Ian Brown, late of the Stone Roses, glimpsed morosely on his own in a pub called the Leaky Cauldron.
As ever with the Harry Potter series, the actors playing the new teacher-intake supply much of the fun. Professor Dumbledore is portrayed by Michael Gambon who, perhaps in honour of the late Richard Harris, does it with a faint Irish accent.
It's all rattling good fun, but oddly, considering that this is around 20 minutes shorter than the previous film, I found my attention wandering more often. Cuaron stages the big set-pieces well but may not have Columbus's gift for driving the storyline onwards at all times, round the obstacles and over the speed bumps.