I've just re-watched the episode and I have to say it was much more enjoyable second time round, in fact I'd say they tied up the story as well as I could have possibly hoped.
Last night, I decided to watch some older episodes to get mysef ready for the Finale, so I watched the first 4 episodes of Season 1 and I'm glad I did now, as it helped me remember what mattered most to me at the beginning of the show: The characters. Of course I was entrigued by the mysteries of the island, but it wasn't that which gripped me all this time. It was things like finding out that Locke had been in a wheelchair, then waiting to discover how it had happened; or when Kate found the letter Sawyer had written as a kid, and his explanation of how his parents had died; or that scene with Jacke and Locke, where he screams "It's never been easy!!" and pleads with Jack to help him press the button because "I can't do this alone".
It's true that they should have given us more answers in 'Across the Sea', but I don't think the Finale was the place to do that, and I'm glad they concentrated on revealing the fate of the characters and I thought they did it extremely tastefully. Brilliant ending to the show.