This film is the standard by which all opera films must be measured.
Zefirelli gets right to work and makes good use of the mournful overture by showing the creditors of the dying Violetta ransacking her formerly grand Paris apartment. We realize with horror at the end of the overture that she is still there, coughing away, in the apartment, while the creditors cart away the beautiful accoutrements of her former life.
The remainder of the opera is portrayed as a sensational flashback as the blues of the scenes shown during the overture give rise to the warm candlelight tones of the party, brilliantly costumed, acted, and sung. The "Brindisi" scene is absolute perfection: meltingly sung by both Placido Domingo and Teresa Stratas, romantic and well-matched leads, stunningly costumed, with a lavish spread on the table that would make Martha Stewart look like a piker.
The middle scenes with Cornell McNeil drag somewhat, perhaps because the country idyll of Violetta is inherently unbelievable, and the lyric soprano singing isn't quite as interesting as the coloratura singing in the first act, and the dramatic singing in the third act.
No matter. The large choral scenes which follow are satisfyingly dramatic, with no less a personage than Natalia Makarova in a dancing role, and Alfredo's denunciation of Violetta is both melodic and superbly villainous.
As the opera ends, we discover, in a cruel Zeffirellian twist, that Violetta's deathbed reunion with Alfredo has been a dying hallucination, as the set fades to the same blues of the overture. Get out your handkerchiefs.