Classic story, original play and excellent acting
Original W. Shakespeare play, including original quotes. Very good acting, actors are of correct age - Olivia Hussey (Juliet) was 15 y.o., Juliet was supposed to be 14 y.o. according to the book.
Fights and death scenes are not too graphic, but mostly realistic. Of course, fully according to the play, main heroes commit suicide at the end of the movie - so prepare to discuss this with your children. One sexual scene, including naked man from the back and women, covered with sheets. For a brief moment Juliet breasts could be seen (note - actress is, technically, minor - 15 y.o.)
Overall, it's a great movie - the best Romeo and Juliet movie so far. The minimum age depends on the child maturity and ability to understand complex topics, such as love, death and fate. I would say 10+ is a minimum, 12+ would be appropriate for most of the children.