The Durgnat book is wonderful, sadly finished as he neared death. It's his overview of the film and various theories, approaches, other critics, production stories, shot-by-shot analysis, and psychological meanings. Whether you enjoy it may depend on what you are looking for in a book about Psycho, and how familiar you are with Durgnat's style. If you've read his early work (of which I highly recommend Durgnat on Film and Eros in the Cinema), you'll know what this book is like: impressions, emotional arguments, insight, literary asides, and the occasional frame-by-frame observations. For fans of the film, it's a delight. But if you're looking for a more formal and literary/psychological/sociological analysis, pick up Robin Wood's book on Hitchcock's Films (and/or ...Revisited). Wood and Durgnat were an interesting pair of critics, working for different journals from the beginning, writing with directly conflicting styles while often having the same conclusion about the value of films. They both loved Hitchcock, for very different reasons, and Durgnat's collection of Hitch articles (gathered in The Strange Case of Alfred Hitchcock) could hardly be more different than Wood's seminal film-by-film analysis. Both keyed on the voyeuristic aspects of Hitchcock's late work, the audience participation, but their methods of analysis were polar opposites. Where Wood is cool, focused, intellectual and precise, Durgnat was vibrant, tangential and sloppy (his errors in simple scene details are infamous among other critics); at a time when there was no easy way to review old films, Durgnat was more off-the-cuff, which may irritate some readers. But reading Durgnat on Psycho is like reading Wood on Rio Bravo, reflecting personally on a film they can "watch" in their heads over and over, with their own peculiar take on what the film means and how it works.Could anyone comments on these books?
A Long Hard Look at Psycho
Alfred Hitchcock and the Making of Psycho
The Robello book is completely different, more concerned with the production of the film. As such, it's like Dan Auiler's great Vertigo: The Making of a Hitchcock Classic, going through the preparation, contributors, actors, filming details, editing, post-production, marketing, and reception of the film. It is certainly valuable for it's collection of information (especially straightening out the erroneous claims that Saul Bass "directed" the shower scene; he was specially hired by Hitch to storyboard that one scene, and did so to match Hitch's description of what he wanted, then Hitch filmed those storyboards very closely), how Hitchcock worked with writers and source novels, etc. But don't expect much analysis.
By the way, my choice for best analysis of Psycho is James Naremore's excellent entry in the Indiana University Press "Filmguide" series from 1973 (which also featured grad student David Bordwell on Passion of Joan of Arc and Gerald Mast on Rules of the Game); it's long out-of-print, but readily available in the usual used internet sites. If you've enjoyed Naremore's great noir compendium (More Than Night: Film Noir in It's Contexts), you may find it interesting to read his early critical effort, which is a bit more formal and dry.
And for a good Hitchcock overview, my recommendation is Focus on Hitchcock (edited by Albert LaValley), which features exerpts from many of the key '60's critics and their often groundbreaking evaluations: Sarris' entry on AH from American Cinema, Wood's great defense of AH as artist ("Why We Should Take Hitchcock Seriously"), Durgnat's early essays on Psycho, Leo Braudy's critique of the Truffaut interview, and a Bordwell-like storyboard of the NxNW cropduster scene breaking down the duration of each shot that impressed me greatly as a teen learning to appreciate how film works.