As usual John Noble delivered an amazing performance, the interrogation scene with Captain Windmark was very powerful and was totally believable that Walters mind was being ravaged as Windmark searched for info. I imagined Michael Douglas in Black Rain tearing apart the gang hideout but that was what was happening to Walters mind.
I like Georgina Haig's character Etta, Daughter of Peter and Olivia, she resonates a mental fortitude and determination that both Peter and Olivia have....or had. I got the impression that both Peter and Olivia were tired...dejected that after everything they went through they still couldn't save their timelines future. Etta felt like she was humanities torch bearer.
After letting the events of the episode sink in and pondering what this universe is going to do to defeat the "observers". I thought to myself what if September fragmented the info betwenn Walter AND Walternate!
And the only way to access it is for both Walters to use the Transilience Thought Unifier Model-11 from their respective universes....in essence a mind meld with both Walters!
The finale scene where Walter is blinded by the sun reflecting off of the CD's also hints to my theory....reflection of himself....on half a disk. I think the sun will also play some part in the conclusion of Fringe...the yellow dandelion, the song Only You by Yazoo.....I did a little Google search and looky at what I found!