When the TNG series premiered in 1987, it wasn't greeted well by many of the old-time Trek fans, including myself. It didn't help matters that one of the earliest episodes, "The Naked Now" was a superficial retread of the classic "The Naked Time" from '66. The new episode should have served as a way of spotlighting several of the new crew, but all it did was show them all in heat. I wasn't too impressed. What did work was keeping the central theme of exploration (something lost in the offshoots, DS9 & Voyager). The new Enterprise was twice as large as the original, with about a thousand personnel aboard. Capt. Picard (Stewart) was a more cerebral, diplomatic version of the ultimate explorer we had known as Capt. Kirk. Again, Picard wasn't too impressive in the first two awkward seasons, as some may mistake his caution for weakness. The Kirk-like first officer Riker (Frakes) was controlled by Picard, so the entire crew of Enterprise-D came across as a bit too civilized, too complacent for their own good. It's interesting that this complacency was fractured by the most memorable episode of the first two years, "Q Who?" which introduced The Borg. All of a sudden, exploration was not a routine venture.
Other memorable episodes of the first 2 years: the double-length pilot, introducing Q; "Conspiracy"-an early invasion thriller; "Where No One Has Gone Before"-an ultimate attempt to define the exploring theme; "The Big Goodbye"-the first lengthy exploration of the new holodeck concept; "Datalore"-intro of Data's evil twin; "Skin of Evil"-death of Tasha Yar; "11001001"-perhaps the best holodeck story; and "The Measure of a Man"-placing an android on trial. Except for "Q Who" the 2nd year was even more of a letdown from the first. Space started to percolate in the 3rd season. I liked "The Survivors"-introducing an entity resembling Q in a depressed mood, and "Deja Q" with both Q & Guinan squaring off, as well as other alien beings. A remaining drawback was the 'techno-babble' hindering many scripts, an aspect which made them less exciting than the stories of the original series. As Roddenberry himself believed, when characters spoke this way, it did not come across as naturalistic, except maybe when it was Data (Spiner), the android. The engineer La Forge (Burton), for example, was usually saddled with long, dull explanatory dialog for the audience.
In the 3rd year, truly innovative concepts such as the far-out parallel-universe adventure "Yesterday's Enterprise" began to take hold, topped by the season-ender "The Best of Both Worlds,part 1" in which The Borg returned in their first try at assimilating Earth. After this and the 2nd part, the TNG show was off and running, at full warp speed. There are too many great episodes from the next 4 seasons to list here, but I tended to appreciate the wild, cosmic concept stories best: "Parallels"(s7); "Cause and Effect"(s5); "Timescape"(s6); "Tapestry"(s6); and the scary "Frame of Mind", "Schisms" and "Genesis." There's also the mind-blowing "Inner Light"(s5), "Conundrum" and "Ship in a Bottle"(s6), "Second Chances." The intense 2-parter "Chain of Command" was almost like a film, and the great return of Scotty in "Relics" was very entertaining, though it showed you can't go home again. The show also continued to tackle uneasy social issues, as in "The Host", "The Outcast", "First Contact" and "The Drumhead" as well as political:"Darmok", "Rightful Heir", "Face of the Enemy" and "The Pegasus." The series ended on a strong note, "All Good Things..." a double-length spectacular with nearly the budget of a feature film. But it wasn't really the end. A few months later, an actual feature film was released "Star Trek Generations"(94). It's rather ironic that the TNG films couldn't match the innovation and creativity of the last 4 seasons of the series. "Star Trek Insurrection"(98) for example, is a lesser effort than any of the episodes mentioned above.