Decent premise, but it's just a bit of a slow watch for me.
That's despite 'The Holcroft Covenant' having moments that either should be or are enjoyable, but in between lies iffy pacing and uninteresting characters. I also found the cinematography lacking, for instance they visit a fair few different countries and yet I never got a feeling for the film's world itself - just scene, cut, scene, cut etc.
Michael Caine is entertaining though, as he always seems to be. I enjoyed his performance, some of his humour early on is good. As for those around Caine, I liked Victoria Tennant, Bernard Hepton and Michael Lonsdale. It is a fairly solid cast, to be honest.
With that said, I finished watching and just felt like it was missing something. 6*.