What are your hot takes? I'll go first

Fly is actually a good episode. I like it a lot. The idea of walter trying to kill a fly is quite funny to me. It's a complete and absurd change of pace from the rest of the show to the point where it's funny. Also, it shows something about Walter's character. It shows that he is quick to anger, which is an important milestone in his journey to becoming heisenburg. In fact, I'd argue that this episode is a pivotal one, possibly the most important episode of the show.