there is certainly some emotional payoff to the church scene in the end, and the island plotline had a satisfactory ending (even while deliberately not explaining outright (excluding jacob's simplistic description a few episodes back) what the island is). there is, relating to the island, also some interesting foreshadowing of events we will not see in hurley telling ben he was a great number two, and ben in turn telling hurley he was a great number one. but, in, effectively making it so that the flashes sideways did not actually (this operative word depending, of course, on one's religious ideology a lot) happen, there is a certain dramatic failure in the screentime arguably wasted (not unlike the flashback/flashforward pairing i complained about a geat deal in "ji yeon" two season ago, which was more the show toying with the audience than a satisfying character or plot moment)

think about it this way: sayid died twice and did not get to be with either shannon or nadia. hurley and libby did not get to be together (instead he spent, presumably, a good chunk of his life with ben). sawyer did not get to spend any more time with juliet (though, i suppose he could have gotten the runner-up prize of spending time with kate, or could have been reunited with cassidy (though, they didn't really have much of a foundation for a meaningful relationship) and his daughter). sun and jin being dead, ji yeon was raised by, well, maybe her grandfather or a series of nannies. locke died misled, a pawn in someone else's game

the good: rose and bernard and vincent seemed to have a nice, happy island life going, and maybe cindy and the kids from 815 joined them or got to go home finally. claire did get to be with her son again. richard did get to leave the island and live out, presumably, a  mortal life. walt didn't get dragged back into the island drama (as far as we know--he was not in the church, so that means the island time was not the most significant part of his life) and might have had a relatively normal life. desmond may have found a way off the island again (i doubt hurley would have restricted travel to and from, as jacob had) to be with penny and charlie

and, as i already said, the on-island conclusion was great, even sans complete explanation. taken as true: the island is the cork on a bottle of evil. t hen, protecting it, in the universe of the show, is important, and the fight between locke and jack was great. and hurley being the new guardian was a satisfying, and appropriate, character and plot ending

the problem, ultimately, comes down the the sideways. in the beginning of the series, the flashbacks gave us character beats, and occasional plotpoints (notably in desmond's episodes). the flashforwards gave us plotpoints (and showed us how much or how little the oceanic 6 had changed). the flashes sideways, though, as it turned out, were not giving us plotpoints--after remembering the island, the various characters did not go back and help out in stopping locke from destroying it--and were only giving us character beats in retrospect... maybe

nitpick: sure the numbers turned out to be the last of the candidates, except those six numbers had been important (separately from the rest of the 354 available) long before there were only those six candidates left. outside the show, they were linked to the valenzetti equation, being variables dealing with controlling the end of the world... but the show, in the end, had no place for science any longer, so the dharma initiative research was gone, the hanso foundation went unmentioned. even widmore, in the end, came back not for dharma-related stuff but because jacob wanted him to bring desmond back

personal (i.e. i might be the only one bothered by this one) nitpick: the outrigger shooting could have been covered about 4 or 5 different times during this season, with ilana's people, with locke and sayid, with miles and richard last night, but we never got it

was lost a great show still, despite the sideways conclusion, despite the "ji yeon" trickery, despite the tattoo episode, despite kate's toy plane, despite the man in black (nor his "mother") never having a name? yes. on a tv forum i frequent, someone quoted alan moore:"not without it problems, i'll confess; but then, without them, could perfection be?"