One of the criticisms leveled at TNG is excessive political correctness, and no episode is more worthy of the criticism than this one.
What's amazing is that we spend the first 15-20 minutes of the episode without this even being an issue - we just get Geordi and Data boring us to death with discussion of fixing the engine and training Data's cat.
But then, horror of horrors, it turns out that warp drive is the 24th century's version of the Ozone layer hole (or global warming). I guess this idea might have had potential, but the execution here is terrible. The aliens are totally unsympathetic and the less said about the idea of a speed limit in space, the better.
I guess the one scene in which Data trains spot is a dim star in a very dark galaxy of an episode.