Really good episode. The storyline has really been picking up. Peter becoming all Observer-like is awesome and I enjoyed his Valkrying of the Observers in this one. John Bishop is as awesome as well and I laughed at the Marathon Man reference and the David Bowie thing.
I think it's safe to say that Peter has been the main character this season while Olivia has been relegated to a supporting role. Hopefully she'll set up more as Peter begins to lose himself.