Here's the song, in case you don't remember it:
Here's the movie via Youtube.
The New York Times says, "In Alice's Restaurant, Penn has made a very loving movie, but the loving is not verbalized; it is sung and seen, in sequence after sequence" and closes with this:
Through it all, Arlo maintains amazing grace, which provides both the theme and the continuity for a very original movie whose structural weaknesses couldn't bother me less. With a film as interesting and fine as Alice's Restaurant, structural weaknesses, seen in proper perspective, simply become cinematic complexities to be cherished.
DVD Talk calls it "a casual, laid-back memento of the Woodstock year". Roger Ebert gives it 4 out of 4 stars and calls it "faithful to the spirit of Arlo Guthrie's original recording". Rotten Tomatoes has a critics score of 67%.