Of the three Rilke biographies that I have read (Ralph Freedman and Wolfgang Leppman being the others), this one was the most consistently satisfying. Prater purports to concentrate more on the personal aspects of the poet's life, and, comparatively speaking, I think that he succeeds. There is less of the not always helpful literary commentary in which, for example, Freedman indulges, and by comparison the Leppmann book has more of that snapshot quality about it that seems to be such a tendency now in biographies written by German authors--as examples I am thinking here of Gregor Martin-Dellin's book on Wagner, and Ruediger Safranski's books on Nietzsche and Heidegger.
In this book there is a greater sense of continuity with regard to the inner workings of Rilke's personality and emotional life. And we know that the evidence for that inner life is most rich, and like any other writer dealing with this poet, Prater does not always take everything at face value because of what he describes as Rilke's continuous habit of "self-stylization". If you wish to read and own a single Rilke biography, this is really the one!