Common Sense Media is a really helpful website for finding family-friendly movie reviews for both old & new movies.
What they offer
They provide trustworthy information and tools, as well as an independent forum, so that families can have a choice and a voice about the media they enjoy.
The site provides independent reviews, age ratings, & other information about all types of media.
Why it's great
I really like that they provide a general review and age rating and then they also give reviews by both parents and kids. This gives you a really good sense of what the two different audiences think.
Here's a quick example of what kind of information it shows for the move Despicable Me 2:
The age rating feature is especially useful, because at a quick glance, you can see whether you might want to permit your children to watch the movie or not!