Playtime, said to be Tati's favourite of all his films, is often cited in lists of top 100 films. Not having seen it before I bought a copy (from MovieMail, so much more reasonably priced than the exorbitantly priced BFI) and viewed it.
It really is quite an extraordinary film, with minimal dialogue, and the camera flitting from scene to scene in the first part of the film particularly. The second part of the film is mainly set in a restaurant that has only opened that day, and shows every facet of the restaurant, for example, electricians trying to finish the neon lighting over the entrance just as the first customers are arriving, staff ripping away protective covering from the floor surface just as the same couple are entering the restaurant, and so forth. Tati himself is seen in much of the film, often recognised by men who were in the army with his character, Monsieur Hulot. Other characters who appear in many different scenes are a coach load of splendidly behatted American tourists.
The film can be seen as an allegory of modernity. It has touches of Chaplin and Keaton about it and I am sure is one of those films that can be seen many times, the viewer gaining something more on each screening.

In many ways, Jacques Tati's epic masterpiece "Playtime" is an unlikely candidate for best comedy ever -- but it's a title that no one who's seen the film could deny. The film is nearly dialogue-less for much of its length, and there is no plot to speak of. In the first half, Tati emphasizes the dehumanization of urban living, as his hero Monsieur Hulot (played by Tati himself) wanders around a cold and impersonal city, stumbling into the strange dilemmas that result from a mechanized existence. The humor is similarly cold and distant here, as Hulot appears as just one tiny ant amidst an entire teeming anthill of rapidly shuffling life. But the film opens up in its second half, which represents Tati's solution to the coldness of modern urbanity. Here, in the hour-long restaurant scene that fills the film's second half, the chaos and warmth of humanity begins to break down the hard lines of urban architecture. This scene is set in a recently opened restaurant which seemed to have been constructed with little regard for its eventual use by human beings -- its layout is awkward, its bar puts constant barriers in front of the bartender, its chairs either fall apart or leaves marks on the occupants' backs. This is an urban space that seems designed to leave human eventualities completely out of the picture. But once the restaurant opens for business, it becomes apparent that urban construction is no much for the sheer human determination to have fun, and the restaurant explodes with life and vibrancy. As the party builds towards a frantic pace, the restaurant begins literally falling apart around the revellers, in an utter masterpiece of comic destruction. Accompanied by the constant bop of a jazz band, until they give up amidst the chaos, this scene surges and seethes with life crammed into every corner of it. Mini-narratives play out everywhere as characters slide in and out of the frame and the camera goes searching around the room for people to follow. It's a glorious mess on screen, but Tati keeps it firmly under his control, and always rioutously funny. It's one of the most brilliant scenes ever filmed, and one wishes it could just keep going forever. But eventually it ends, the last partiers spill out into quiet morning streets, and the film ends with a carousel of cars suggesting the cycle of urbanization and re-humanization that was just observed in microcosm. Truly remarakable.