Once More, With Feeling was always a brave experiment with a high chance of being shot down by both critics and fans alike.

Most of the greatest moments in Buffy's history have come as a surprise the audience. However, in this case, Joss Whedon had been hyping the event for several months now - so expectations have been enormous. That he has exceeded most almost everyone's expectations is, therefore, all the more remarkable.

The episode begins in an unconventional fashion. It features the obligatory "Previously..." montage but no teaser or traditional titles. Instead, we get a delightfully cheesy new title sequence that spoofs matinee movie musicals.

The action begins in the Summers' household, with the Scoobies silently going about their morning activities (except Buffy, who seems determined to stay in bed as long as possible) to an overture by Chris Beck.

The action then shifts to Buffy on patrol, an act she now considers to be "Going Through the Motions". Slaying several vamps and a trio of dancing ghouls before rescuing a gorgeous hunk, Buffy admits to the world that she just wants to feel alive. The choreography is as slick as the humour.

Next day at the Magic Box, Buffy discovers that she isn't the only one bursting into song. Even Buffy writer and former musical-comedy actor David Fury is singing in the high street about his dry cleaning.

The gang leap into research mode - and into a Gilbert and Sullivan-esque piece. Willow thinks that they may be trapped inside someone's Hollywood nightmare, Xander suspects witchcraft (before hastily backtracking due to present company) whilst Anya naturally place the blame squarely on the shoulders of bunnies.

Bursting into a diatribe backed by a rock track and light show that would do Meatloaf proud, Emma's Caulfield marks herself out as a very talented singer indeed.

Emma's wonderful performance, however, is dwarfed by the might of Amber Benson's rendition of I'm Under Your Spell - Tara's love song to Willow. It's trippy, it's hippy, and it's totally beautiful. If I heard this on the radio, I'd rush out and buy it.

It's all fun so far, but there's always a dark side to anything that happens in Sunnydale. A singing and dancing demon is in town and people are dancing themselves to death. They are also singing about their innermost feelings - things they would never speak out loud.

A Xander and Anya duet is up next in a scene reminiscent of a Doris Day musical comedy. The couple sing and dance in their silk pyjamas, revealing the little things about each other that really get on their nerves. Again, the choreography is as good as anything you'd see on a West End stage.

Later in the day, the couple join Giles to discuss events. As they walk through the streets, cleaners dance in the background and Marti Noxon cameos as a woman trying to sing her way out of getting a parking ticket. She's a really gifted vocalist too.

By the time night falls, Buffy has caught up with Spike to discover what he knows. All the vampire can do is open his heart through song, however. James Marsters turns Billy Idol, hijacking a night-time funeral and dancing on a coffin as Buffy tries to keep him under control.

This may be a highly irregular episode, but that doesn't mean that the overall season arc has been forgotten. A stray remark by the increasingly kleptomaniac Dawn leads Tara to discover that Willow has been altering her memories of the row they had.

As the shy Wicca leaves the Summers' house to find her girlfriend, Dawn is kidnapped by creatures resembling giant ventriloquist's dummies and brought before Sweet, the demon causing all the commotion. The young actress performs a stylish dance routing with Sweet's henchmen before the demon goes all Jim Carey in The Mask with his chameleon-like zoot suit and snappy leg work.

Meanwhile, Buffy has returned to the Magic Box to train with Giles. In the excitingly-staged Standing In The Way, the Watcher admits that he feels he's holding his Slayer back - worried that she has become too dependent upon him. The effects in the scene are subtle but stylish, with Buffy slow-motion training mixed into Giles at normal speed.

Tara has arrived at the Magic Box, closely followed by Spike and a captured henchman. The gang discover Dawn has been captures ("Dawn's in trouble? Must be Tuesday," notes Buffy wryly!)

Buffy heads to the Bronze to rescue her sister and encounters Sweet. Joss Whedon's love of 70s prog rock shines through in Life's A Show. Bizarre time signatures and stunning dance moves from Gellar make this something special. As does the revelation to her friends that Buffy was plucked from Heaven rather than Hell at the start of the season. When Giles calls for backup, Willow and Tara don't fight - they just sing and dance behind Buffy. Hilarious.

With Sweet sent packing, there's one more song to sing as the Scoobies ponder Where Do We Go From Here? Spike has had enough at this point and storms out - chased by Buffy. The couple kiss passionately - and this time, Spike isn't dreaming. Where do the go from here indeed?

Once More, with Feeling is totally indulgent but never once suffers because of it. Having Marti Noxon and David Fury might sound dumb on paper but works perfectly. Not everyone will know who they are, but it's a big plus for those in the know.

Nobody puts in a weak performance, although Amber Benson, Tony Head and Emma Caulfield must be singled out for special praise in the vocal department. The choreography is also something special - the fruits of many weeks of intense training for the cast.

The production values are sumptuous too, with far more location filming than normal and genuinely creepy villains. Even the main story arcs are progressing within such a complex framework - this is no stand alone episode.

It's difficult to know where Joss Whedon should go from here - surely he cannot top this for sheer quality and invention?

What the press said

Picking apart the technicalities of this Buffy episode is the best way to miss the point of how beautifully it worked, how gracefully paced, clever and affecting it was. For one thing, Whedon figured out how to make the music a seamless part of the action, by working it into the plot as a joke. Salon.com

What makes the episode special is the way that Whedon uses the music, not as a gimmick but as a way of moving all his major storylines along. The genius of the musical genre is the way that characters will express thoughts and feelings in song that they would never say in speech, and by inflicting the entire population of Sunnydale with a spell that forces them to sing and dance, all sorts of awkward secrets come out. New Jersey Online

Most numbers are delightful and contain enough surprises that to describe them would be dampening part of the joy. Buffy [is] smart and surprising in so many ways, is no Cop Rock — and that's a compliment. New York Post

This risky hour won't suit everyone, not even every Buffy fan. But an hour of series TV that stretches in new, ambitious directions is something to sing about. Denver Post