Couldn't disagree more with the previous reviewer. I found the characterisation to be subtle, the plot engaging and the denouement moving. I was an undergraduate in the early sixties so am a contemporary of the protagonists. Apart from the occasional idiomatic anachronism - nobody said 'A big ask' in the sixties - I found its depiction of the period convincing.
Given that tastes differ - some people enjoy reading Jeffrey Archer - don't write the series off without giving it a try: one episode should be enough to see whether it grabs you or whether you find, like GTBarker, it's not your cup of tea.