I loved this episode and am loving this final season!
Peter becoming so Observer-like that it is scaring the crap out of me and Olivia as well. His attack on the Observers was something out of a horror movie.
Walter is afraid of becoming his old self which is a real danger by the way he talked to Nina so brutally about Bell's lack of feelings for her. I find it fitting that Walter is struggling with this. It's the perfect setup for the resolution of his character arc.
The quest to assemble the anti-Observer weapon seems to be almost over. How many tapes do they have left to watch, you think?