In my original, very first watch-through, this was the first episode that really stood out to me. It is not, in retrospect, notably more brilliant than the other episodes (though it is a great episode nonetheless). I think it is more the resonance of some of the feelings and emotions it explored with some of the things that were happening to people close to me. While episode 1 was the episode which more apparently explored the theme of suicide, this was the episode that, I thought, wove and lingered around the subtler sentiments around the act. It is a comparatively simple episode, but nonetheless one that is quintessentially Kara no Kyoukai.
You would want to have watched this episode before moving on. Folks who have yet to watch this amazing film series: watch it now! You’ll find few better uses for your time.