I do like what they're doing with the flash-narrative. I've always appreciated the elegance with which they used the flashbacks to lend context to the present - the way a word or phrase at the end of the flashback could prompt you to reevaluate a characters actions over the entire episode, as you realise they knew something all along - and though you'd think a flashforward would be the same process in reverse, they're still managing to make it all about the island (since showing you where somebody's going gives you insight into their motives, and goals, in the present). It's a great way of adding depth, and cultivating that feeling of "I have to watch that again".

I'm especially enjoying Desmond's flashback episodes. They appeal to my sense of twisted metanarrative humour...