Common Sense Media covers all types of media -- books, movies, TV, video games, apps and more. You can find both objective and subjective information. It's rating system covers messages, violence, sex, language, consumerism and drinking, drugs & smoking. Any time I'm told a show is appropriate for my kids, I'll check it out here. If there is something I object to, I still may let them watch it but at least I'm able to talk with them afterward and provide balance with our beliefs. To me, those discussions are the foundation of teaching them how to make good decisions in the difficult, high-pressure situations that lie ahead for them.
The Internet Movie Database covers film and TV episodes. This one is less parent-oriented but it does have notes for parents and stresses that its reviews be factual and not generalize with comments like 'not too much violence.' Like CSM, it provides great details so that you can determine if 'potty language' is okay but stronger four-letter words are not or how prevalent kissing scenes are.