Pulp Fiction is my favorite movie ever made, because every time I watch it I look at it totally differently.
For instance, the 1st time through, I just sat in awe of the total masterpiece I was watching. The 2nd time, I noticed some of the deeper themes in the movie. Like: Tony Rocky Horror only touched Mia's hand at her wedding. Through the story Vince battles his temptations by Mia, and at the end of their story, all he touches is her hand, when he shakes it
THis is a great film to show to your child when they start to develop opinions about plot and story, and not just relying on action to make a movie enjoyable. Pulp fiction contains no action at all, and when your kids start to express an interest in character development, show this to them. There are much more adult films than this, and this is intended for humor, rather than violence.
The reason this got an R rating is by far the language, sexuality and drug use. If your kids aren't influenced by language in movies, I HIGHLY recommend it. Just know, it doesn't portray the mob life positively. The characters are given choices to leave the life, or not. the ones who do, live happily and the ones who don't... well you'll have to watch the film to find out.
The screenplay is phenomenal, the direction is fantastic, the performances are spot on, and the story is flawlessly presented. If your kids understand any of that, this is highly recommended for them.