With the return of the Oceanic Six covered ("316") and the adventures of John Locke off the island recounted ("The Life and Death of Jeremy Bentham"), only the travails of the characters back on the island remain to be covered before bringing all three groups back together in some fashion. That story turns out to be the rise of Sawyer as the leader that so many, particularly Hurley, felt he could be.
Sawyer comes into his own in a big way in this episode, and it is a major advancement of his story arc. Gone is the Sawyer that would have concerned himself solely with his own survival and interests. He is now as capable a leader as Jack, and perhaps a better one at this point. The three years with the Dharma Initiative certainly have something to do with that, but he was already taking charge (with Juliet's able guidance) once the time jumps stopped. (And it's fun to note that Miles essentially took up Sawyer's previous role as the sarcastic challenger to Sawyer's assumed authority.)
The episode itself is relatively straightforward once the pattern was recognized. Most of the actions jumps between 1974 (when the Oceanic Tribe first encounters Amy) and 1977 (when Amy gives birth). Sadly, the impact of the final scene was completely obliterated by the ABC promotional staff, so what probably would have been relatively smooth foreshadowing felt heavy-handed and obvious.
The beginning of the episode dropped a few interesting clues and details. Just before Locke turns the Frozen Donkey Wheel back into its proper position, the Oceanic Tribe notices that they are in the ancient past. A huge Egyptian-style statue can be seen in the distance (ostensibly the source of the "four-toed statue" from "Live Together, Die Alone"). That links to the hieroglyphics seen at the Temple site (and for that matter, the Swan Station, the door for the controls to Cerberus, the Frozen Donkey Wheel, and Hurley's drawing of Egypt in the previous episode), and continues to build evidence for ancient origins of the island.
One interesting note involves Jacob/Christian Shepherd. If the Oceanic Tribe (and John Locke) were in the ancient past when the Frozen Donkey Wheel was turned into its proper position, then Jacob/Christian Shepherd appears to be independent of the normal passage of time. Either that, or Jacob/Christian Shepherd was caught up in the time jumping as well.
It was a great idea to have the Oceanic Tribe "stop" in the 1970s era of the Dharma Initiative, before whatever catastrophe was mentioned in the Swan Station orientation film. This presents the perfect opportunity to fill in the gaps in the Dharma part of the mythology left from earlier seasons. Most of the scenes are meant to explain how Sawyer and the rest came to be welcomed into the Dharma Initiative, especially when there was no reason for Horace to trust them at all. Saving Amy was a nice start, and preventing a war with Richard was even better. But it was mostly about Sawyer's decision to step up to the plate and keep his people on the island long enough to find the rest of the Oceanic Tribe.
The location of Rose, Bernard, and the others in 1974 (and 1977, for that matter) is still to be resolved. That appears to be a bit of a plot hole, but it's also something that could be easily answered later in the season. Less clear is how Richard could remember John Locke (and presumably, now the man with the really fake facial hair), yet seem not to know them in the months after the crash of Oceanic 815. And if that red-headed child was supposed to be Charlotte, that's an apparent continuity error; according to Ben's litany in the fourth season, Charlotte wasn't born until 1979!
Paul's ankh necklace is an interesting little artifact, because it could link to the gigantic statue earlier in the episode. The statue appeared to be holding two ankhs, one in each hand. The ankh is a symbol for eternal life (perhaps a connection to Richard and the unusual prope