This superbly put together "little people" episode plays out somewhat like the pilot to a spinoff series. (And actually, it would be an interesting experiment to do two Star Trek shows on board the same ship at the same time, with one dedicated to the command crew dealing with the tough decisions, and the other featuring the junior officers working for them, wondering what's going on in the secret briefings and trying to figure out ways to move up the ladder... although the idea might work better as one show, divided into A and B stories.) As a standalone episode, "The Lower Decks" is the perfect idea for a series this late in its life, as it gives the writers new territory the Star Trek franchise has never before explored, and lets the audience, after six years, finally view the command crew from a different angle.
The true genius of the episode lies in the makeup of the five leads it features. Rather than just creating five new characters out of thin air, the writers go with something old, something new, something borrowed, and something blue (okay, it's more like green). Nurse Ogawa has already been established as a continuing character by this time, and her presence gives the audience an anchor. Ensign Sito, borrowed from "The First Duty" (the popular fifth season episode) is a doubly fine choice, as the character already has a backstory and the actress is magnificent to boot. These familiar faces serve as a bridge to getting to know the two new junior officers, Lieutenant Lavelle (who is more or less the featured character of the episode), and his Vulcan roommate, Lietenant Taurik. Rounding out the newcomers is the smiling civilian bartender, Ben, who wears a green jumpsuit and acts like he's been serving bar at Ten Forward for seven seasons.
To the benefit of the episode, the writers don't simply develop a "junior" story that's centered on these characters, abandoning the more familiar command crew in the process (which would defeat the point of seeing an episode of the show from a different point of view.) Captain Picard and his people are still dealing with a crisis and are still making weighty decisions; we just don't get to see these actions from their perspective and only learn about their decisions (and the consequences of them) when they affect the junior officers. This adds a mystery aspect to the story that already has humor and drama, making "The Lower Decks" not only one of Star Trek's most unique offerings, but one of TNG's best.