FORMULA: Tuvix + The Child + Second Chances + Up the Long Ladder
WHY WE LIKE IT: Has a lot of heart.
WHY WE DON'T: Magical science.
REVIEW: Let's get it out of the way first, because it's a major issue when dealing with this episode - the science that enables it makes no sense. In fact, it's really on par with some of Voyager's science fantasy humdingers. Similitude presents a jellyfish-like creature that, injected with any DNA, turns into a fast-growing, short-lived clone that - and this is the really stupid part - has the memories of its donor at whatever age it currently appears to have! And Phlox had that dubious creature right there on a shelf all along! It is a ridiculous conceit that undercuts the emotional drama because in a sense, you're continually distracted by the clone's improbability. And yet, without the duplicated memories, you have no emotional drama at all because the clone would not be able to even generate a personality in 7 days. (Give the symbiote a telepathic link or something at least!)
Now, that all said, the episode still has a heart. We get to know "Sim" and young Trip simultaneously, though the scenes where he is younger don't really stand out. The 8-year-old Sim is engaging enough (with a scene that harks back to Archer's childhood in the pilot), but teen Sim has the wrong accent and attitude. When Sim reaches adulthood, we get into the real meat of the subject. By then, he's a thinking, even existential, being and we feel for him (despite his improbability). Through him, we explore the human condition: What would you do if you had only a few days to live? (Blow every secret apparently, as this plants the real seed for a relationship between Trip and T'Pol.) Would the brevity of that life make it more or less precious?
Archer's attitude may seem controversial, though I think it hits just the right (albeit very dark) note. In a very real sense, this is Tuvix done right. Archer threatens to "murder" Sim, but we understand why (Sim is grasping as straws and endangering Trip's survival, on which indeed hinges the Xindi mission). And Sim, in the end, comes to his own senses, and acts very bravely despite almost making a run for it. Instead of unwarranted murder (as in the Janeway/Tuvix story), we have a story of noble sacrifice.
The B-story about Enterprise being trapped in a particulate cloud and Sim coming up with a way for shuttlepods to tow a very crusty starship into safer space is a fun bit with nice effects. It's only really noteworthy because of Sim's contribution and his struggle to take Trip's place. That, along with T'Pol's farewell, Porthos' role, and Sim and Phlox's last exchange, makes the funeral and the beginning and end poignant and relevant. The episode is structured so that either version of Trip could be in that casket, but a switch would have been a little more drastic than similar "replacement doubles" in Deadlock or Visionary. Still, if Trip had had to go, that would have been an impressive accident/stunt to have him go out on. Whoa Nelly.
LESSON: Don't drink the milk passed its expiration date.
REWATCHABILITY - Medium: Affecting and thought-provoking, with fine, sensitive performances from the regulars (a hallmark of Levar Burton's direction), but the premise leaves something to be desired.