One of the most overrated movies of all time, the PG version generally available on DVD is the 1973 remake, not the 1968 release. According to today's rating standards, I think this movie would be rated PG-13 or R. In any case, it's not something I'd want to show to 13 to 15 year olds, or any susceptible young people already being bombarded by the "if the feeling is strong, it can't be wrong" message from all sides.
It's been a while since I read the play, but the movie version makes it clear that the young lovers spend a night in fornication before their "marriage." After the couple's secret marriage by Friar Laurence, there's also an extended nude "morning after" bedroom scene and, at the end of the movie, the swelling violins seem to approve their suicides as tragic, but essentially noble and admirable, acts.
Artistically, I found the movie a bit sappy. The couple sometimes seemed like modern kids trapped in Shakespeare's world and unable to make sense of the times and sensibilities that his words reflect, and attempting to impose a modern realist theatrical technique on an Elizabethan play that was written a few hundred years before Chekhov or Stanislavsky were born. This may be one reason why so many of Shakespeare's words were left out of the film, and why bedroom, fighting, dance, crying, and other wordless or almost wordless scenes were so drawn out.