Up until, the flashforwards haven't shown much involvement within the Oceanic 6. We know that Sun and Hurley seem to have broken away; we knows Hurley's now institutionalized, and in the last episode, we saw the real reason Sayid has become Ben's hitman. About the only thing that's been unclear is what has been leading Jack from the stable person we saw in 'The Beginning of the End' and 'Eggtown' to the tottering wreck he was in 'Through the Looking Glass' It's even harder to believe him from the opening scenes of this episode, where he seems to be playing house with Kate and Aaron, more at peace than he's ever been at any time on the series.
But as everybody who's been watching the show by now knows, Jack is his own worst enemy. His compulsive need to fix things lead and need to constantly do better have shaped him all this way. All his life he has been under the strain of being Christian's son, and he has loved and hated his father for it. Maybe he thought that on the island he could get away from it, but as we've seen repeatedly, Christian is still a presence on the island. Now, not surprisingly, the pressure of his father is what leads to him destroying the first really good thing he's had in his life. Even after all the things he saw on the island, he still can't accept the evidence of his eyes. He'll only get there after he completely destroys himself.
All of this is accelerated by a visit to Hurley, who in the years between his return to Santa Rosa really seems to have lost any impetus to help himself. He is now convinced that everyone on the island is dead, including Jack , Kate and himself. It's hard to argue when you know that he's seeing his own ghosts --- the difference is, he now believes them. Jack tries to stave off his own problems by proposing to Kate, but all that does is hasten his own degeneration. In a sense, we saw Jack destroy his marriage to Sarah because he couldn't let things go, and he essentially does the same thing involving Kate. It's hard to figure out what kind of promise she's keeping for Sawyer, but his mere mention seems to completely unseat the foundation of their relationship. (This is supremely ironic considering what will happen when Jack does return to the island)
In the here and now, the major action doesn't have a lot of suspense. Jack's suddenly coming down with appendicitis isn't much of a cliffhanger, considering that the very flashforward demonstrates that he will survive it. What is far more telling is how much Jack tries to control even his own surgery. There is something very telling in the fact that even though Juliet is performing the operation, he still wants Kate to be in the room. Indeed, Bernard has to chloroform him for anything constructive to happen. Equally telling is what Rose has picked up (and what might have concerned the fans as well). If nobody on the island has gotten sick, and the healing process is accelerated, why did Jack's appendix suddenly become infected at such a critical point? We know the island won't let him die, but it's becoming clear that it also doesn't want to let him leave.
Meanwhile, in the jungle, Sawyer is leading his own group of people back to the beach. He seems determined to protect Claire and Aaron from something--- as if he knows there's even more danger out there for her. (Then again, a smoke monster and a bloodthirsty band of mercenaries is pretty dangerous on its own.) He runs into Keamy and the mercenaries, who are bloodied, but not completely broken. (Widmore must be paying them millions to keep this up). But it's all futile, because in the end, he loses Claire in one of the more shocking scenes of the episode. Claire wakes in the middle of the night to see Christian holding Aaron, something that would be difficult for a ghost to do. Claire says "Dad?", we get a scene break, and when daylight comes Claire is gone, and she's abandoned Aaron. There was a popular theory on the net that everyone thought Claire might have died while in the barracks. Since we now know that this is not the case, the question arises: why would the island choose to separate Claire from her baby? Why does Christian appear both to Jack and into Claire, aside from their filial bonds? For that matter, why did Miles, who said he saw Claire walk into the woods with a man, just let her do it? Maybe he thought that Claire was already dead. Still, a guy in a suit appears in your camp, and you don't let anything happen. Seems like Miles has been taking his lessons on the island from everyone else.
Sawyer and Jack seem to be in the process of reversing roles. Jack will deliberately hurt everyone around him, have a singular obsession that rules him, and will end up broken and alone. Sawyer is becoming heroic, making bold talk, rushing out to save people. And given the way things are on and off the island, it's looking like Kate still won't be able to make a clear choice between them. Even now as the series winds down, she doesn't seem to have been happy with either one. Perhaps her final choice will come down to Aaron. 'Something Nice Back Home' is a pretty good episode, and given the information that we get, we can't exactly classify it as a filler. There were some great dialogue between Miles and Sawyer (a match made in snark heaven) a little revelation about Charlotte that makes Jin reveal his brutal side yet again, and all those Jack and Kate shippers must have loved the flashforwards. Still, considering that the main action seems to be happening in the jungle and back on the freighter (what the hell have Sayid and Desmond been doing the last two episodes?) I can't help that it feels a bit less developed than the rest of Season 4. Jack may be tottering on the brink of his sanity, but he doesn't know that the real craziness is still to come.