I couldn't agree or add much more with the positive reviews already posted here. I first saw this film in the 60's on "Saturday Night at the Movies". The film was introduced by the star, Michael Rennie, who spoke to the continued timeliness of the underlying theme of the movie. I now own this particular DVD version of the film and I have to agree with the less favorable reviews of some others give here that focus on the technical failings of this reproduction (not restoration).
Nonetheless the message of this movie is still relevant. I have read that a remake is in production but the focus of Klaatu's concern will be our disregard of the damage being done to our planet in general rather than specifically the nuclear proliferation threat emphasized in the 1951 film. There are also rumors that the film may return to the final twist of the short story "Farewell to the Master" written by Harry Bates.
Let's hope that with a remake coming up the studio will reissue a properly "restored" version of this classic on DVD.