For the most part this was one of the best episodes of Black Mirror. In fact if could have been my favourite if it weren't for the disappointing ending. The idea of them being in a simulation the whole time is basically a high tech version of the old "it was all a dream" trope, which tends to be quite a storytelling cop-out.
During the episode, when the characters mentioned the possibility of them being in a computer simulation I thought, surely the episode wouldn't end up with such an obvious and unoriginal ending. Yet that's what we got. and it wasn't even done particularly well in contrast to the rest of the excellent episode. It just came across as corny and contrived.
Overall a brilliant episode which deserve a far better conclusion.
Overall a brilliant episode which deserve a far better conclusion.