I thought the episode was okay, but it kinda went a bit too far when not-Ash became "real". For the first half-hour it seemed like the story was taking place 10-20 years in the future, then there were suddenly replicants. I'd say it was actually my least favourite episode so far, although it was still enjoyable enough.
As for The Entire History of You
, it was my favourite episode of the previous series, so a feature version of it should be cause for celebration. But it's Hollywood, so my initial reaction was that they'll probably butcher it and change it from being a story of mundane horror into some sort of cop story. Then I read this
For the film version, the story will be set in a near future where technology that allows users to re-experience past events, and follow a man who reconstructs his relationship to his dead wife - from her point of-view - and unknowingly uncovers a vast conspiracy.