Many people poo-poohed TNG when it first aired. But when this episode hit, things turned around. “Did you see that one with the brain worms? That was sick!!!” Brain worms have invated Starfleet. Picard must go on the offensive and phaser the slimy buggers. There are some twists and turns, some clever moments and (for its time) great special effects. A classic.
I’d say this would have to be in my top ten. I saw this when it first aired and it had the creepy sci-fi elements that just hooked me on Trek. Sadly, even though a sequel to this episode was hinted at in the end of the episode, it was never meant to be…