It offered substantially better colour fidelity and resolution, with approximately double the number of dots per line (the standard measure of analog video resolution). They could actually represent a better picture than broadcast analog television - in practice, little improvement over standard VHS was visible when viewing material recorded off-air.
To view the better picture, a direct video connection to the monitor was required, ideally a component connection. Older television sets tended not to support this, negating much of the improvement in picture quality.
Home S-VHS decks never became popular outside of Japan, probably mainly due to their high cost, lack of prerecorded content, and the lack of visible performance improvements in playing off-air recording. S-VHS camcorders did become popular for high-end amateur work, as it allowed for at least second-generation copies (necessary for editing) to be made at a reasonable quality.
S-VHS is now mostly obsolete, as it has been replaced by DVD for playing prerecorded content, and by the various digital video formats for amateur and semi-professional video production.