The Inner Light is one of the finest TV series episodes ever. And for many Star Trek fans, it actually is the best ever.
What distinguishes this episode is the brilliant script. I cannot go into a lot of detail without spoiling it for those who have not seen it, so all I can say is that it is centered around Jean-Luc Picard and that it holds the "story of a lifetime".
Without Patrick Stewart, of course, this gem of a script would not have the same impact. I recommend this to everyone who wants to be introduced to the best of the Star Trek Universe, but not as the first TNG episode: it is better to be already familiar with the Captain to get the full experience of the Inner Light.