I think IS is a truly unique tool that has to be levied properly to be useful--as such, the context of where and how it's used really matters. For most situations I've found the implementation of IS in a mobile environment fairly useful. Such as when viewing text messages or emails. Desktop applications are far less common and the one's I've seen implemented don't really do much. They end up only hiding content until you scroll down--which on desktop is pretty useless and causes friction between an end user and your content.
It's niche, but I do believe there is a place for it.