If you talk about the plot of Fly it is the worst episode of the entire show. 47 minutes of two people hunting a fly sounds like the best idea for a filler episode. Before I watched this, I really thought Fly is a filler episode, just to have 13 episode in this season. After watching it I can say, that it has the worst plot of the entire show, but Walt and Jesse are there too and the dialogue between these two characters is till now the best dialogue in the entire show. They carried this episode and I can finally say, that I would never say, that this is a 10/10, but I can say, that this is a really special episode.