Burton never better!

He totally owns this film, which while having plenty of flaws is basically a pretty decent one, even if a bit overlong.

Of Burton's films, I've probably only seen a handful:
The Robe
Alexander the Great
Cleopatra (though not in a very long time)
The V.I.P.s
Night of the Iguana
Who's Afraid of Virginia Woolf

but I feel he is perfectly suited to his role here. As serious as this film is on the surface, Greene has injected a fair amount of subtle humor, which Burton delivers flawlessly in deadpan fashion. And I don't know if I've ever been so in awe of that voice as I was in this film. It could also be that Elizabeth Taylor was so bad, that you couldn't help but see how much better her husband was faring.