While Reddit is one of the best sites on the internet, it does not take much time or effort at all to stumble to one of the many subreddits or areas where there is pornography, explicit content, explicit language, and other generally not safe for work (NSFW) content that could be perceived as poor for children. Even the front page can have pornography available on it at times. As such, while excellent in every other way, it can be less safe for children.
The following is content common on the site, it is rude callous and young boy esque
"24 points 36 minutes ago
I got my dick in my hand and I'm waiting. Now what?"
"8 points 3 hours ago
i dont think shes the kind of whore to post pics on the internet, shes more the "ill sleep with anyone! lol!" kind of whore.
I don't know how this site can qualify as "Excellent" for child safety - it frequently (depending on the area of the site you browse) contains or links to sexual content, with little or no warning. A lot of the users' content also contains swearing and sexual innuendo. However, it is a good resource for cute pictures.