The thing that I really like about Natural Born Killers is the soundtrack. The songs are almost iconic to me now because of the images in the movie they are associated with. Granted, I may be a little biased because the soundtrack was produced by Trent Reznor, but you can't listen to any of the songs from that soundtrack without instantly associating it with the movie.
The editing is also rather good, if by good you mean kind of crazy and ADD. It's almost like a two hour long music video. The way the images and music fit together is perfect for me. The duality of satire of the violent nature of the media and the way it uses the violence in the movie to draw you is amazingly crafted. It opitimizes 90's cinema in my eyes.