All bad things come to an end, and "Emergence" ends a streak of relatively weak episodes that dominated the latter half of TNG's final season. Within that streak, it probably does better than most; a silly, nonsensical story is improved by some amusing touches.
The oddball characters on the train (especially David Huddleston's conductor) offer plenty of chuckles, as does Data stopping a car with his hand.
Unfortunately, the moments off the train are far weaker - a bizarre story (the Enterprise developing a consciousness?) that incorporates a technobabble sci-fi solution.
But hey, at least it's better than "Bloodlines" and "Journey's End".