Black Mirror is basically a series of often darkly comedic parables or satirical vignettes riffing on elements of our modern lives. Episodes usually focus on a singular idea or theme that are taken to not entirely preposterous but provocative extremes. The pilot episode 'The National Anthem' is as good an example as any and arguably the strongest episode so far (although I loved 'The Entire History of You' which my other half tells me Robert Downey Jr. has picked up to make into a full length film). With Charlie Brooker being the acerbic commentator he is, there's usually a lot of really funny and biting incidental stuff in each episode as well, besides the overarching idea/theme.
I highly recommend watching it though, terrific television. The most recent episode 'Be Right Back' I thought was interesting, but yeah, it didn't have much of a payoff given its length. The idea seemed to run its course within the first thirty minutes or so and after that it just sort of veered off-road and petered out. Nevertheless, looking forward to next week's episode.