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.