In the alternate universe, we have another potential spin-off, with Miles and Sawyer partnered as LAPD detectives who also fight crime at night. Actually, it could be part of the same Locke/Ben spinoff, if they teach school by day and fight crime at night. I'd watch that show.

But even where the sideways story is fun, the alternate universe is one of the biggest pieces of frustration at this point. We don't know what the stakes are in the alternate timeline. But we seem to be learning more, and at this point, I find the explanation that this is what would happen the these characters if not for the influence of Jacob and the Island, to be the most compelling. See this comment from JL at Sepinwall's for more discussion of when the timelines diverge.

I still suspect that the Island characters and the alternate reality characters are going to end up at similar places, even if they get there in different ways, because that's who the characters fundamentally are. At this point, if the AR stories play out to be the epilogue-in-advance, wouldn't they effectively erase the events of the entire series? If so, why not just say, "it was all Walt's dream?"

Perhaps as it continues to become clearer, the flashes to the alternate universe will play better on a second viewing. But one of the appeals of Lost is that most episodes play well as individual stories as well as part of an overarching narrative. And at this point, instead of being able to enjoy these stories for what they are, we're spending a lot of time trying to figure out what they are and if they ultimately mean anything.

While the show has hinted about the contours of the world-spanning conflict involving Charles Widmore, bringing Widmore to the Island suggests that we may be about to delve more into it. He's arrived with a sonic fence and a sub. Mixing Alan Dale into the Island mix should be fun to watch.
While I had been frustrated with the show ignoring some of the elements, it's worthwhile remembering that the writers and producers of the show are also big fans of the show and they don't intend to let major pieces of the puzzle slip away.

And speaking of the overarching narrative, what happened on the Island for the Others between the time that the Oceanic 6 left in 2004/2005 and the Ajira flight landed on the island three years later? The characters we followed on the Island -- Sawyer, Jin, Locke (original recipe), Juliet, Miles, Charlotte, Faraday and Frogurt were unstuck in time, Billy Pilgriming their way across eras while the frozen donkey wheel under the Orchid skipped off its axis. When Locke turned the wheel to fix the time skips, the characters we followed spent their next three years in the Dharma Initiative in the mid-70's. We have an idea of what happened with them, as well as what happened to the Oceanic Six after they got home. But the audience doesn't know what happened on the Island. Have the Others been at the Temple ever since the end of season 3?

Time is one of the more interesting features of Lost as a series. More time passed off screen than we see with our characters in the present. Part of that may be due to the fact that so much of the story is told through flashbacks or forward. But as the audience, when we've watched 6 years of character development and interaction, we may tend to value these relationships more than the characters might, because of the whole time factor.

Perhaps this is only frustrating because of the hour per week pacing of the show: half of the main cast disappears for episodes at a time. Sawyer was turning into the world's forgotten boy; we haven't had much time with Sawyer since "The Substitute." This episode doesn't involve Ben, Jack or any of the characters with them back at the beach. This has been a feature of Lost's storytelling since at least Season 3, when we spent too many episodes with Jack, Kate, Sawyer, Juliet and Ben on Hydra island and very little time with Hurley, Sayid, Charlie, Desmond, et al back on Craphole Island proper. And it's a result of the fundamental narrative characteristic of the show: Lost has always, with a few exceptions, focused on a single character each week. The time that other shows would spend on B-plots is used to serve the flash stories. Because we don't yet quite know what the stakes are in the alternate universe, this might be hurting the show's momentum from week to week. Aside from the obvious reality that it would be woefully inefficient to assemble half the cast and send the crew to a different location for a couple of minutes of a C-story, it might be nice to not completely ignore the pieces of the game that are out of view. I suspect that on a faster viewing schedule, this won't be as noticeable. I realize what I find lacking about this season of Lost is simply more Lost.