If you haven't yet seen the lost series finale, I suggest you put off reading the below post until you do. Anything after the break may contain significant spoilers.
Say what you will about the series finale—who died*, who lived, what was wrapped up, what was never addressed**, what questions were answered, sort of answered, left unanswered, &c—one of the major strengths behind the show is the establishment of an interesting, consistent mythology that is slowly revealed (I hesitate to say "explained") to viewers via effective storytelling.
When writing a short story, novel, screenplay, or television show, it's not enough to have interesting characters and a cool plot; you have to be able to advance the story and explore the psychologies and depths of the characters in an engaging way. Simply put: it's not enough to have a great story, but you need to tell that story well, too. The what is necessary, but the how is absolutely essential. It's character development, it's maintaining the relationship (often tension) between what the characters know versus what the reader/viewer knows (dramatic irony, anyone?), it's controlling pacing, it's telling your story in the best order, &c &c. If lost had been told from the point of view of the smoke monster (what the hell is his name, anyway?) from the very beginning, or if the show had unfolded in strict chronological order (starting with Jacob's birth and ending with the series finale), the show wouldn't have been nearly as effective as it was.
Granted, there were some pretty big questions that were left partially or wholly unresolved, and I don't necessarily recommend that M.O. when writing your novels—readers like loose ends tied up, even if it's not perfect. I also tend to think readers don't really like abstract church-afterlives vaguely reminiscent of the Restaurant at the End of the Universe, either, so I'd also avoid that tack if possible. To each his/her own.
As for the ending of lost in particular: I think it was interesting and competent, but not totally mind-blowing. I didn't like that major questions weren't answered (e.g. what the island actually is, the fates of certain seemingly extraneous characters, the source of Eloise Hawking's apparent extra-temporal awareness, and so on), but I suppose those weren't really "the point." I'm not sure I could really tell you what "the point" was. I did, however, think the bookending of the eye opening/eye closing image, while predictable, was nice, and while I wasn't really a fan of Christian being there (though I suppose, being dead, he did belong), I did like the "reunion" feel of the church scene. It may grow on me as time goes on.
What do/did you think, fair readers?
[Edit: speaking of you, fair readers: there are now 1,000 of you following PMN! Thanks to everyone for reading, commenting, and following!]
* Everyone? I think?