Great Walter-centric episode. I love how Walter's LSD trip went from goofy to heartbreaking to downright chilling. I deeply fear for him by the end of the episode.
I'm glad Peter is back to his old self and that he is relying on Olivia as an emotional anchor. I hope no more bad things happen to them. They've been through enough with their daughter's disappearance, their separation, their daughter's death, and Peter's Observer near-conversion.
I love that the show hasn't forgotten the consequences of the alternate timeline storyline and now that the Fringe gang finally have the Observer boy, we may be on our way to the beginning of the final epic fight aganist the Observers.
My theory about Donald: Donald is really September. September somehow turned himself into a normal human being which he has used to conceal him from the other Observers.