I confess, I find David Lean's original 1940 something film very dull indeed. This is quite interesting for a number of reasons - it doesn't work - but it is quite interesting.
Firstly, it has a very bleak aesthetic style. The feel of the film is anything but romantic. It's quiet, frustrated, almost existential in execution. There is very little score (and what there is is crap anyway) and the tone is very low key throughout. it's actually a guilty feeling film, bleak and possibly more genuinley 'British' than the original.
Secondly, Burton doesn't over act. He doesn't grunt his way through the performance but it is very low, and shameful in delivery. Burton is playing the typical englishman - guilty to want pleasure and guilty of having it.
Sophia Loren does a fine job. She can say more with an introspective look than some of the risible dialogue she has to handle.
Sadly, the story doesn't gel. It's just so low key that, maybe, stupid slushy moments would have served it better. And there are plot elements that go nowhere and Loren's character feels guilty about having the affair because she's neglecting both work and family. And as for Burton getting the job offer in Australia...less said the better.
However, despite its flaws, it's nowhere near as bad as everybody makes out and by the end you'll be slapping your forehead and wondering why Loren didn't run off with Burton!! The alternative existence being awfully dull...