It was quite a ride from beginning to end. Totally worth waiting a whole summer for! I absolutely loved it. I like how they addressed a couple of the mysteries from last season and added more than a few to this season as well as mapping out the direction for what's going to happen with Fringe this year. I also like how the characters seem to be developing. Walter's still as kooky as ever, able to alternate between directing Astrid on how to make custard while doing an autopsy, Broyles strange connection with Nina Sharpe and her implications on his character, Olivia breaking down only to get stronger as she becomes an unwitting piece in a war they're only just beginning to scratch the surface on, and best of all Peter. Peter is starting to emerge more as a force in the division. He's no longer just his father's babysitter and junior scientist. I like that he's beginning to take a more active role in the division and the lead that he took in this episode when Olivia and Broyles were unable to do much. Peter in fact saved Fringe and I loved his take charge attitude. There also seemed to be a more pronounced chemistry between he and Olivia. The only minor, and by minor I mean teensy tiny little nitpicky detail that slightly irritated me. When Peter ran off after the shapeshifter, he didn't have a weapon so...how was he supposed to stop it? The female agent already tried shooting it and it didn't work, so what was Peter going to do? Cut it with his scathing cynical comments? Shoot it down with sarcasm? Least he could do was grab the gun that Olivia dropped and try to shoot it in the head.
To me that little pea in the mattress was the only detraction in one heck of a fun episode. Bring on the rest of the season!