As some of the other comments have pointed out, episodes 1 and 2 are good but not great. There's a review on AV Club [1] that address it really well, but the general sense is the producers were not quite sure what tone to strike. They tried to mix shock value with sci-fi, a bit of audience pandering and some humor, and it ended up kind of flat.
Episode 3 is where it really takes off. I won't give spoilers but it hit so hard I later realized I wasn't prepared for it. I watched it twice to see whether or not it still had value outside of the "shock", and even the second time I found that it was a fascinating look at where we might be going.
EDIT: I forgot to mention, Robert Downey Jr. bought the rights to turn episode 3 into a movie. The story will center on a widower who uses the technology to reconstruct a vast conspiracy. [2]
[1] http://www.avclub.com/tvclub/black-mirror-the-national-anthe...
[2] http://www.theguardian.com/film/2013/feb/12/robert-downey-jr...