First 4 episodes were great. Episodes 5 and 6 were not. It turned sappy and complicated. I don't think they explained all the plot lines. Too bad! I really liked it at first. It was hugely popular here, but many articles complained about the ending.
We did watch the last two episodes and, while I can see what you are saying, we found the last episode gripping (if a bit far-fetched) and the denouement with the young terrorist convincing. As with other Jed Mercurio shows, plots tend to be very dense, if not impenetrable. All in all, we like it.
I read it it will be on Netflix in the US in the coming months.
Have you seen any of his other shows...Critical and Bodies? They are hard to find here.
To my mind, Keeley Hawes is one of those British national treasures (like Nicola Walker)--ubiquitous in English television programs--always leaving a memorable impression.. Line of Duty, Tipping the Velvet, MI-5 (Spooks in Great Britain), The Missing....all excellent performances.
According to the IMDB, she will be appearing in three upcoming series now in post-production....Jerusalem, Summer of Rockets and Mrs. Wilson. Always look forward to her appearances....