What are your thoughts on “Fractional CFO’s?

Seems like I've been seeing this more and more recently - interim CFO at my company has done it, and seen it on Twitter a bit. Wondering if anyone here has done this or plans on doing this in the future? What are your thoughts on this? Would like to hear what you think about this as your career, but also from an employee perspective (how would you feel about having a "fractional" boss?).