Well, I thought it was a good finale, the last scene with Jack was pretty powerful I think.
But I'm still pretty iffy about the whole "sideways timeline is actually purgatory" thing, I sure hope that was just symbolic because I thought the writers would come up with something less cliche than that.
I can accept most of the things the writers threw our way. Polar bears, magic black kids, electromagnetic islands, crazy scotsmen in hatches who are immune to radiation, evil smoke monsters, haunted cabins (they never explained that one), mediums, time travel, fountain of youth, fate.
But purgatory? No, that's going too far. And as Lateraus said, many unaswered questions.
Like the big one for me is, what the f*ck happened to Michael, Walt and Mr. Eko? Where were they during this big happy reunion in the afterlife? Apparrently Michael is still trapped on the island as a spirit, well that isn't fair, is he being punished for killing Ana Lucia and Libby? Well what about Ben and Sayid? They killed a sh*tload of people and in a much more cold and sinister manner, all Michael wanted was to get his kid back. And WHY did the smoke monster kill Eko? Also a question never answered.
Is there just a "no darkies in heaven" policy?
Well Rose was there so that's not it.