When this episode first aired, I was just a kid and didn't much appreciate it. To me it was dull as dishwater. But then I was a kid, and what do kids know, right? The nuance and philosophical undertones were lost on me. As was the fact that this was quite probably the best episode of TNG up to this point in the series.
It's a classic Trek morality tale, well-written and deftly-executed. The episode builds up quietly but effectively, culminating in some pretty electrifying courtroom scenes. Riker's case against Data (and the fact he dissembles then deactives him) is plain devastating and there is a powerful twist added when Picard seeks guidance from Guinan, who deals the wild card: this is an issue that has implications of slavery. That this observation is delivered by an African-American actress makes it all the more powerful and stirring.
A powerful episode...although I must question Starfleet's initial declaration that Data is their 'property'. A legal loophole maybe, but sure as hell paints Starfleet in a scarily fascist light.