Following in the path of "Clues", "Night Terrors", "Cause and Effect" and "Conundrum", this episode sets itself up as a mystery. It's not clear why Riker is so tired all the time. Worf has an unsettling experience at the barber, Geordi experiences hallucinations and Data disappears with no recollection of what happened. There's a disturbing experience on the holodeck, and pretty soon the entire Enterprise is at risk. Riker saves the day, but the conclusion leaves us with more questions.
Oddly (but effectively), this episode throws in a bunch of humor to keep the viewer off balance. Mott the barber gives Worf a lecture on Klingon hair. Data gives a hilariously awful poetry reading. (Is Picard on a date here? Weird.)
Not quite a classic, but an enjoyable episode.