I think that some of the reviews of Humphrey Carpenter's book on Auden have undervalued its contribution to a genuine understanding of both Auden the man and his work.
To begin with, no life of Auden could avoid the taint of being "gossipy." Auden led a completely messy life complete with all manner of free and easy sexual encounters. Auden not only led this kind of life, but documented it for the amusement of similarly inclined friends. No one who examines the primary source documents, letters, diaries and even poetry can do anything more than to write a gossipy life. When not only menages a trois, but menages a quatre are the norm, it is impossible to write any other kind of biography unless the naughty bits were rendered in Latin as they were formerly in Suetonius..
What I liked about the book is that Carpenter breaks Auden's inner life into three distinct phases. At Oxford he was under the spell of D.H. Lawrence and even Freud. During the hungry thirties, like most European intellectuals, it was Marx and Communism. It appears that time in Spain contributed to Auden's disillusionment with "the God that failed." His third intellectual period was more orthodox embracing the Anglicanism of his youth and Kirkegaard coincided with his the beginning of his years in New York City.
For me, Carpenter's book filled in a number of blanks for me, mainly concerning Auden's emigration. Knowing more of the work than the man, I was under the impression that Auden decided to take up residence in America at the beginning of World War II rather than nearly a year before. His return to Oxford and Britain coincided with failing health and desire to return to his native land (though still an American citizen).
Another aspect of the work that I noticed was a shift in Auden's work in his later years. Critics have, I think unfairly, blamed the decline in quality of the poems on residence in America. What I think Carpenter demonstrates is that while Auden's poetry lost some of its edge, Auden was becoming more settled, more domestic in his later years and perhaps for this reason the themes involved more commonplace topics. Perhaps in reaction to these critiques, Auden tended to disown some of his more important poems, including the famous "September 1 1939", with its indictment of the thirties as "a low dishonest decade" (a poem that had particular resonance for me after the financial crash of 2008).
The picture that Carpenter paints of Auden is a person who probably would be better read than lived with. He was in a constant state of dishevelment and his living quarters were always characterized by visitors for the profound state of untidiness. Still Auden did write some of the best verse of the 20th century and even branched out less successfully into the fields of opera (Stravinsky's "Rake's Progress) and even the theatre (the work here seems to be dreadful, proving no one can be good at everything). As a teacher, his methods appear to be original and oriented more toward making students think about what they were reading (a sample exam on Elizabethan literature, "explain why the devil is both sad and honest.").
I think that Carpenter does an admirable job in this life of Auden. I think that other than a thorough read of Auden's collected works (and there is yet to be published a single good collection), this is probably as good a work on Auden as one is likely to find.