Ebert's take on the great movies is an enjoyable read. Ebert gives lots of interesting tidbits about each film and provides context for each film within film history. Followed by
The Great Movies II and III. For the other side of film criticism, try
I Hated, Hated, Hated This Movie, which is a terribly fun collection of bad movie reviews. Few things are as delightful as a good bad movie review.
