You can watch the beginning of the film here at Mitchum's Facebook page.
Bright Lights Film Journal calls it "riveting" and says it is "usually ranked as one of the best of the genre". Images Journal says it is "An essential noir and one of the great archetypal noirs." FilmReference.com has an article. It's one of Time's 100 Best Films.
1/13/2008: 1001Flicks has a review.
8/11/2008: Movie Zeal has a review as part of a month of noir.
5/16/2009: Noir of the Week has a review.