I just watched the episode, and it was the worst ep of Fringe I've ever seen. We've had eps without one of the three main characters before, but never eps as crappy as this.

This show succeeds on the strength of its triangle created by the three strong main characters, Olivia, Walter and Peter. They all love each other, and their love bridges universes and reaches through time and apparently makes anything possible. They play off each other in an entertaining manner and draw the audience's sympathy and interest. Removing one character temporarily from the triad show the importance of the triad all the more vividly [witness the Peterless eps at the beginning of this season], while removing two of them at the same time, the way Letters of Transit did, removes the show's dynamism and hook. I don't care how awesome John Noble is as an actor [though he is awesome]; Walter alone, as he was for all of about 5 seconds of this ep [until Peter showed up at the very end] cannot carry an ep of Fringe himself.

Having established that this ep was particularly stupid for removing Olivia and Peter for most of it, I would also like to say that it failed spectacularly by eliminating Olivia completely from this ep. [Somehow Anna Torv got top billing in this one, though she did nothing.] What the hell, Fringe?! Olivia is the mainest of main characters. She is the protagonist, the one we've grown attached to and invested in. The unspoken rule of narrative is that every single chapter has to involve your protagonist [prologues and epilogues excused]. This was neither a prologue nor an epilogue, and thus it constituted a completely Olivialess irrelevant tangent. I don't care how interesting an ep of Fringe is. If it doesn't have Olivia in it, it doesn't count. This glaring structural flaw of Letters of Transit left me feeling narratively cheated.

Also the characterization of the Observers as Nazi-like dictators with a lust for power and control contradicts everything we know about these passive, morally ambivalent, wise, yet also emotionally kind of clueless characters. If that's the direction the fifth season is going in, I have better things to watch. I was really hoping for a wrapup to all the plot threads about the shapeshifters and the machine and Peter's reappearance and why he's so important and the holes in the universes and Olivia's "recovering" memories and Walternate's capture of Olivia and how the hell David Robert Jones came back and where the Observers came from, etc., etc., etc., NOT the Fringe team struggling against some cheaply imagined dystopia.