It's obviously just for SDTV... but
It's substantially better than the competing interfaces:
1. Composite RCA: Exhibits "dot crawl", which is the annoying-as-hell patterns that seep together at the edges of patches of color. EEK
2. RF: very ugly, prone to nasty disturbance patterns and also exhibits dot-crawl.
S-video sepperates chrom and lum, so you get pretty much get as much as can be gotten from a standard definition TV, but that's not a whole lot (720x480 interlaced). Still, it's better than the alternatives.