Well, the scenery and locations didn't disappoint. They're absolutely gorgeous (filmed in Scotland I believe).
Agatha Christie stories are pretty rote so the bar isn't too high, but this two-parter didn't manage to clear it.
The body count was really too high for Our Hero (Luke Fitzwilliam) to sink his teeth into any one murder and frankly while he did ID the killer in the end ... he was one step behind the whole way, unlike say Miss Marple.
About the casting and the plot line:
I was very distracted by the fact that David Jonsson's left eye is much smaller than his right. There are many many closeups of his face where this affected my ability to focus on the plot.
Apparently in order to justify casting a Black actor in the lead role, they gave him a back story as being from a rich Nigerian family and coming to London to work in a diplomatic post as an attache to some British muckymuck. He speaks with a posh accent and there is almost no relevance to his African background in terms of the plot.
We get some stereotypical racist comments about "mud huts" from the local high and mighty lord of the manor, but almost everybody else in the film basically just accepts him and appears virtually color-blind. In 1954 rural England? I dunno about that.
Also, he's not given much to do, other than to wander around snooping, and then give a knowing smile in almost every scene.
The dialogue he was given to say didn't help at all.
I couldn't help feeling, this would have been a much better production if they'd just stuck with a snoopy old maid like Miss Marple as the detective.