"The Americans" was the second or third photography book I was ever exposed to, the first "Photography" by Upton and Upton, (a classic intro textbook in its 6th or 7th version now) and the other, "The Portfolios of Ansel Adams". It contains two of my all time favorite images, "Trolley-New Orleans" and "Restaurant-US 1 leaving Columbia, South Carolina" I believe American Photographer did a major article on the 25th aniversary of publication and I have the issue in a box somewhere. If I dig it up I'll post any interesting comments.
As far as the book is concerned I think the crticism was that it presented a pretty lonely and joyless view of America. There are not a whole lot of happy or smiling faces in its pages. When I first viewed it in 1982 I was unaware of such musings and just found many of the images resonated with me. Looking at the images recently I am struck by how many deal with old age and death.
Someday I would like to see the actual prints, but I do not know if they still exist together as a portfolio and what institution holds them. Perhaps on the 50th anniversary of publication (2009) there will be an exhibition.