I've long been a fan of Metacritic. When it comes to getting an overview of what the critics are saying, there's no better site. Metacritic compiles reviews from many well-known movie, music, and videogame critics, weights them (1-100), and presents them as a whole score. It also lists all the reviews with their weighted score. Here's a complete explanation of how the scoring system works.
The result is an easy way to see which films, albums, or videogames are worth seeing, listening to, or playing. You can read all the individual reviews that they've compiled or just take a quick glance at the synopsis. You can also find a lot of great stuff by looking at the All-Time High Scores in each category. Yo u may be surprised at some of the movies that were universally well-regarded.