I came to this book never having read any of Graham Swift's novels (most famous being Waterland and Last Orders). That probably puts me in a minority, since I had no particular prior opinions of the author, but having heard that this book was a collection of short non-fiction essays and reflections on writing was enough to intrigue me. I'd say that it is indeed accessible to others who, like me, haven't read Swift's novels and may even inspire people to read them - though I should warn you that, since it includes some discussions of some of his books there may be spoilers.
This collection consists of essays, interviews, biographical pieces and poems. The poems, as others have said, aren't really up to much - to be honest, I only read a few. The rest, however, was generally interesting, although obviously the various parts will appeal to different readers. Swift describes interactions he's had with a number of others, including fellow authors and behind the scenes types like publishers. Personally, I found the episode with Kazuo Ishiguro most interesting, because he's an author I do know and there's some discussion of The Remains of the Day.
Even without caring particularly about Swift's past, I found the biographical parts of the work still held my attention. Perhaps it's just that they're well-written and convey a human element. It's also interesting to read about how a writer goes about writing, though Swift emphasizes that he's only offering his personal approach - not claiming to be typical or offering a 'how to' model for aspiring authors. In his case, for example, he makes clear that his writing isn't autobiographical or drawn from life, but entirely fictional.
What I found particularly interesting were Swift's reflections on the purposes of fiction, which first emerge in the opening piece (a discussion of two of his earliest memories: polio vaccination and meeting Santa) and are further developed in a lecture 'I Do Like to be Beside the Seaside,' in which he observes that fiction must exist at the borderline of reality and helps us to understand what it's like to be someone or somewhere else.
The pieces are generally short (10-15 pages or so mostly, usually preceded by brief introductions setting the context), so it's easy to dip in and out as your mood and inclination take you. It's not essential to read them all, although for the most part they follow a chronological development so maybe something's added if you read them in order. I assume this collection would be of interest to many enthusiasts for Swift's novels, but I can certainly vouch for the fact that parts of it at least can appeal to literature buffs with no knowledge of the author - and that to me marks it out as a good read.