There are hardly any plot details I can mention without spoiling, except there is very little about it (due to the subject matter) that I found enjoyable. However, it there is no denying it is an immensely powerful piece of filmmaking that is very well written and performed. The attention to detail, particularly regarding previous events and dialogue is exceptional.
It all unfolds in a series of memorable scenes involving Walt and other characters like Jesse, Jane, Skyler, Jane, Donald, Saul, Walter Jr and Holly. Some of the moments that tie together themes involving fathers and daughters are cleverly and ironically written in the build up to a brutal final scene that will likely stay with you forever. I find it a thoroughly disturbing experience, not just for the shock scene, but also for the casual dishonesty each character seems to show towards each other.
It is a crucial episode in the character development of Walter White and one that has ramification for other characters and events depicted in later episodes. Overall it is one of the most important episodes in the overarching narrative of the show.
The one ray of light in it all (in a darkly funny way of course) is the banter between Walt and Saul Goodman. Bob Odenkirk is on hilarious form in this scene and Bryan Cranston plays off him brilliantly.
The visual storytelling is a credit to cinematographers and actors. I also love the early scene that involves a particularly effective reveal of a certain character standing in the background at an important event.
Cranston is generally amazing throughout and is supported wonderfully by the likes of Krysten Ritter, Aaron Paul and John de Lancie. Hard to believe it's the same actor who played Q.