The first 30 minutes or so of this episode continue at the extremely high quality of part 1. There are plenty of highlights to be mentioned, but I think perhaps the best is Riker's monologue in the ready room, followed by his conversation with Guinan. Very well-written.
The episode flags a little near the end. The writers had some difficulty finding a convincing way to defeat an invincible foe (Michael Piller wrote part 1 not expecting to be around to worry about the conclusion), and while this conclusion is satisfying enough, it ends up being a little thin given the buildup.
Finally, the ending with Picard staring out the window into space - trying to come to terms with what he's been through - ends the episode on a perfect not.