At episode 5 I was about to start my review with just 3 stars but it would have been unfair to write about something without finishing watching it...
Dark, yet not scary. Ominous without startling. Goosebumps towards the end. Its structure fairly resembles to the film Memento with linear discontinuity revealing the beginning at the end. Inaccurately predictable it will keep tricking you but you will always have that sense of the big picture. You have most of the answers from the beginning to questions yet to be asked given to you like on a chess game.
The quality of film, or series in this case, is measured by its aftertaste, by the meditative silence you submerge yourself into once "The End" hits the screen.
I'm glad I watched it till the end.
Congratulations Mr Flanagan and team.