I really love it myself. It’s part of my flow at many of the sites that I use for reference in my day to day. I’m probably going to use search once I get there anyways, and this saves me having to find the search function. That might be more a mod/admin use case though.
Not at the moment as we do not have full page search.
Since you mentioned it, I do like the idea of a full page search as well. 