I might try it again, it got to the point where they were visiting the man that was a sympathiser and I switched off. It felt a bit like Starship Troopers (that isn't bad I suppose) but I just wasn't captivated at the time.
Edit: I thought I'd add that that episode did take me two tries (I fell asleep during the boring part the first time, but watched it again 'cause I had faith inspired by every other black mirror episode).
Edit Note: It is a very front-heavy(not sure what word to use there) episode.