"Confirmed Dead" is a bravura piece of pure genre storytelling, and there's nothing else to it. "The Beginning of the End" put everything in place for the rest of the season, and "Confirmed Dead" had the goal of pushing the story even further, really introducing us to the world of season four, and introducing us to the 'freighter four', if you will, and accomplished its goal very well.
The episode flashes back to the freighter four, Daniel Faraday, Miles, Charlotte, and Frank Lapidus all around the time the wreck of Flight 815 was 'discovered'. Daniel's is still the most interesting and enigmatic flashback (Miles' is just confusing and bewildering), simply because I just don't know who that woman is, don't understand why he was crying, and am also connected to him emotionally more than any of the other freighters. Charlotte's dig in the Tunisian desert was definitely a 'what the hell?' moment and is still a lot of fun. I like my polar bears to be skeletons in a desert a billion miles from where they're supposed to be, they're more interesting that way. Frank Lapidus was supposed to fly 815 eh? Interesting. I don't think there's more to him as a character, but we will probably see a Daniel flashback and a Charlotte flashback in season 5.
Naturally there is not much depth to the proceedings, but the action/adventure stuff on the island is pure adrenaline, Miles' awful couple of lines of exposition excluded, and it's just a bravura piece of storytelling in just about every way, and genuinely suspenseful at times. I'm kind of surprised that this episode holds up on repeat viewings, but it really does. It may not be up there with the show at its absolute peak, but it's definitely a great episode in its own way.