tl;dr: You don't need to be familiar with the source material, though I highly recommend watching them.
First things first, early reviews of the movie seem to indicate that it does not share it's source materiel's narrative and thematic focus, and ends up being a fairly generic sci-fi action flick. Of course I've not seen the movie yet, but I don't think it will really count as part of the franchise.
That said, I don't think its narrative competence matters anyway. Ghost in the Shell's animated entries are spread across 3 separate "continuities," as I like to call them. Basically, they are 3 different storylines that share the same setting characters, and (to some extent) themes, but tell entirely different stories:
- The original '95 Ghost in the Shell movie and it's sequel, Innocence.
- The Ghost in the Shell: Stand Alone Complex TV show, it's sequel TV show 2nd Gig, and the sequel movie Solid State Society. (There's also a Laughing Man compilation movie which condenses the core plot of the first show.)
- The series of short movies entitled Ghost in the Shell: Arise. These are less about philosophy and more about political suspense/thrills.
What this means is that any of them will introduce you to the same characters and settings, but they will be alternate versions of them. The focus and style of each continuity is different from each other. The movie, from what I understand, is partly its own continuity and partly an adaptation of the '95 movie. That said, I'd need to see it first to say for sure.