Utterly Awful
I've spent the last few days revisiting the 1945, 1965 and 1974 versions of this classic story (as well as playing the fun computer game with its totally different ending!) and have to say that the only way I could give the 74 version more than one star of ten would be if I forced myself to watch the dreadful 1989 version for the first time since 1990.
This film is beyond awful on all levels. And I'm not simply talking about the changed location, because the 1965 version managed to still be an entertaining romp even with its changed location. But therein lies the problem. This movie was made with the SAME script used nine years earlier (which itself recycled about 75% of the 1945 Dudley Nichols script) and as a result if you watch the films back to back you get a remarkable textbook lesson on the difference between credible acting/directing and awful acting/directing. In the 1965 version the actors deliver their lines with crisp, natural efficiency and we get a good sense of movement. But in this version, EVERYONE and I mean EVERYONE is uttering their lines at a pace of two or three words at a time before they pause and take a breath before resuming and even then they keep their voices in a low hard to follow almost whisper. It makes the whole action on-screen just flat-out boring and you have to blame the director for this because this problem is affecting not just the foreign actors who didn't speak English primarily but even Reed, Lom and Attenborough seem to take forever to get their lines out. Considering how this director also chooses to give us a static, dull shot of someone watching a helicopter approaching that seems to go on forever over the credits (if he thought he was aping Lawrence of Arabia, he failed miserably) I guess the actor's insomnia like delivery is in keeping with the tone he wanted.
Let's also look at how in copying verbatim the 65 version, a lot of things suddenly make no sense. In this one, Armstrong (that's another gripe of mine about this and the 65 version. They keep calling his character "the Doctor" instead of "Armstrong" as if they think we'd forget his profession) and Cannon (couldn't they have just gone back to Wargrave if they were keeping him English??) don't plant something in Vera's room to make her scream and trigger the fake death scene. Are we to believe this was all improvised by chance? Others have noted the "I told you to stay in your room!" line of Blore's that makes no sense because the old scene that established that wasn't used in this one.
Attenborough in particular needs to be singled out for a truly awful performance. He looks like he's had unconvincing makeup slapped on him and he also utterly fails to convey any sense that there is more to him than we realize. Oliver Reed isn't much better. Elke Sommer I think could have done better if she'd gotten some better direction and some better supporting players. As for the rest, the increased focus of giving us different nationalities for parts that started out as historically English only calls attention to their pointlessness in the script and how ultimately they are in effect telegraphing the lesser importance of their characters overall.
Skip this one completely. The 45 and 65 versions are the ones to stick with for cinematic versions (and no, do not watch that Russian version others overrate so much)