This is the first of two books by the same author (see Later Auden)and I'd recommend buying them together as they are terrific accounts which tell Auden's story (mostly) in terms of his poetry. (John Fuller's commentary (on the poetry) augments these very well).(H. Carpenter for the best intro bio.)
Why I liked these books is that they don't expose a bias regarding Auden's life (Auden tends/ed to divide critics) and the poetry (always the first casualty) isn't neglected. There's too much of value in these books to try and paraphrase them but rest assured they will not disappoint. As usual though, the whole controversy over the attitude of certain critics (Jarrell/Leavis/Eagleton) is passed over. Still, really useful. I'd say the same for the Collected Prose, the Dyer's Hand, Forewords & Afterwords. Hendon is a bit spotty but maybe useful (and affordable) for undergrads, while the Sea & The Mirror is rather specialised (Art & Christianity), maybe to be tackled later.
Early and Late Auden are not so much 'academic' works as they are real portraits by someone close to the work, the writer and his times, so there isn't that distance you sometimes feel where authors set out "to do Auden". Great value. Will not disappoint.