She's engaged ... they have a relationship ... already that has me concerned about the message that sends. Then you add in the sex and nudity.
I find it ironic that as a society we tend to agree that teens should have less sex, and yet all the YA books and PG-13 movies are full of it. And then we're surprised that teenagers engage in sexual behavior?
So for me I wouldn't but not really for the specific instances, but because of the themes that I think they represent that aren't great for kids. Besides ... there's so many other and more uplifting movies out there. Why reach back in time for a movie that's iffy? If you as a parent are on the fence, then you might as well just pick something else that you're not on the fence about.
YMMV.