Doesn't come to life, so suffers in comparison to the works of Wodehouse himself. It's a diligent and comprehensive but rather flat essay, rattling off facts in an efficient chronology, but lacking in passion, or even original insights about its subject. There are numerous notes, but there is no superscript marker when reading the chapters, so you don't know when there is additional information, which is intensely irritating. He also contradicts himself, eg emphasising that PGW was a loner but then describing another situation as satisfying his need for companionship, and giving contradictory summaries of his academic success (or otherwise). The generally favourable reviews were presumably from his cronies and those wanting reciprocal favours (he's the Observer's Literary editor).
Try to get a copy of Barry Phelps' Wodehouse: Man and Myth instead.