
Follow the Leader (working title: Setup For The Incident Part II) puts two major storylines into prime position for a massive payoff. Thanks to the "resurrection" of Locke, the 1977 and 2007 storylines are equally interesting — finally!
In 2007 the "new" Locke finally arrives at an Others' camp and greets his old friend Richard Alpert. They don't have much time to catch up, or even address Sun's medical problem of asking the same question on a continous loop, because Locke wants Richard and Ben to join him on a trip.
The first leg of the trip is a visit to the Nigerian beechcraft, where the "compass paradox" is officially created. I wasn't going to get into the nuts and bolts of the paradox but what the hell, let's break it into its main pieces:
1. When Locke starts time-traveling, he time-flashes to the Nigerian beechcraft in 2007. Richard meets him there, gives him a compass, and instructs Locke to give the compass back to him the next time they meet.
2. Time-Traveling Locke then time-flashes to 1954, finds Richard at a camp, and gives him the compass as instructed. Since this was Richard's original timeline (i.e. Richard wasn't time-flashing), this was the first time Richard had seen the compass.
3. In this episode, present-day (2007), resurrected Locke leads Alpert and Ben to the Nigerian beechcraft. Resurrected Locke knows that time-traveling Locke is about to arrive, so he tells Richard to go meet time-traveling Locke and give him the compass/instructions from Step 1.
4. Richard delivers the compass/instructions to time-traveling Locke, which initiates the paradox — or more specifically, a time loop with no origin. Richard thinks the compass came from Locke, and Locke thinks the compass came from Richard.
Damon Lindelof addressed the compass question in a podcast following FTL's airing:
DAMON: All we can say first is that what we have done with the compass was absolutely intentional in terms of sort of the broader themes of the show...
Based on this quote I'm led to believe the "broader" theme is the conundrum faced by both science and faith — the idea and/or belief that something had no origin, that something came from nothing. So at the very least it would appear the compass is symbolic in a very cool way.
For just a bit I was fascinated by the possibility that the compass paradox somehow enabled Man in Black's loophole in some way, but after reading the podcast notes it's looking like I overanalyzed it a bit. It would seem MiB's loophole was a matter of convincing a proxy to kill Jacob on his behalf, since he couldn't kill him directly.
That "proxy" would be Ben in this case, who was completely in awe of the resurrected Locke. He and Richard were left with no choice but to follow their new leader, a leader who was hellbent on finding and killing Jacob.
In 1977, Jack is continuing down the path of becoming a man of (mostly) faith. He convinces Richard and Eloise to take him to Jughead so that he may continue Faraday's mission of neutralizing the anomaly at the Swan site. Sayid joins him on this journey but it won't be easy — it just so happens the bomb was buried under the DHARMA barracks, which is now officially enemy territory.

Lostpedia has FTL listed as a Richard-centric but it's not your typical centric devoted to developing a character. It's tough for me to pick top honors for this one, but it's a close call between Terry O'Quinn and Matthew Fox.
I know at one point TOQ himself was unaware of what he truly was, but I'm not sure if that was true while he filmed FTL. His acting is just too good, and just different enough to create intrigue, that I almost believe he had to have some idea of what was going on. There were plenty of hints to the audience at that point, so I'm sure he was reading between the lines if he wasn't explicitly told.
Meanwhile, Fox did a masterful job in the scene where Jack and Kate are held captive in Eloise's camp (more on that in Intangibles). Every episode at this point shows Jack swaying further toward the Locke end of the spectrum and it's so fun to watch the subtle changes in Fox's portrayal.
And of course, major bonus points to Nestor Carbonell for his scenes in BOTH storylines, 1977 and 2007. His calm demeanor makes for some interesting dynamics with some of his peers, especially those who tend to behave like zealots.
Once again there are no discernable weak links in the acting here, main or guest cast.

Which do you want first, the good news or the bad news?
Okay, the bad news: FTL has the dubious distinction of arguably having THE worst example of CGI in the series — the descent of the Galaga submarine. You'll have to see it for yourself to get the full effect, but suffice to say I've seen surfboards displace more water than that.
The good news: the set design for the underground tunnel is very good, as is the visual trickery of showing an old ship and backing up to show Richard constructing that ship in a bottle.
This is another solid directing effort by Stephen Williams, especially in scenes where he captures certain reactions, i.e. Dr. Chang quizzing Hurley, Jack and Kate's conversation with Eloise, and the "love triangle" brewing in the sub.

The first time around I didn't pay much attention to the time-travel aspects of FTL, nor did I know about loopholes and other things mentioned later in the series. But now that I've been able to digest all the different elements of the episode it seems to get better every time I watch it. Knowing the full series arc also makes it more fun to revisit Jack's changing perspective.
Jack's continuation of Faraday's plan is obviously significant, but the debatable part is how important the compass paradox is. I have a hard time believing they devoted 5+ minutes to a Locke, Richard, and Ben detour built around a mere novelty. For the moment I'm holding onto the theory that the compass paradox was actually a necessity.

The best part about Follow the Leader is that it's both mentally and emotionally engaging. If your brain isn't fried by implications of paradoxes or Locke's apparent resurrection, you've still got plenty of opportunities to root for/against characters.
I'm sure there are plenty of LOST fans who put themselves in Kate's shoes and agreed that Jack was crazy for pursuing Faraday's plan. Others were likely rooting for Jack. Others had no idea what to think.
The scene between Jack and Kate in Eloise's camp is one of my all-time favorites because of my emotional investment in it. Jack simultaneously explains the Faraday situation to Eloise while trying to ignore Kate's incessant pouting and hurt feelings. The reason Kate was pouting? This little exchange which happened just moments before:
. . .
JACK: If we can do what Faraday said, our plane never crashes, Flight 815 lands in Los Angeles. And everyone we lost since we got here — they'd all be alive.
KATE: And what about us? We just go on living our life because we've never met?
JACK: All the misery that we've been through... we'd just wipe it clean. Never happened.
KATE: It was NOT all misery.
JACK: [Sighs] Enough of it was.
. . .
Wow. That might be the first time I stood up and gave a standing ovation to a fictional character.
The bottom line is this episode had something for everyone; if time travel wasn't your thing you still had a linear storyline to invest in and even some "shipper" stuff.