Daniel's development as a writer draws heavily on John Irving's own biography, with vaguely similar books published in similar years, and a similar trajectory to success. Irving acknowledges as much in his afterword, though he's careful to point out that his character's life differs greatly from his own. Despite that, and perhaps because it took Irving many years to write, this feels like a highly self-indulgent book.
It's been some years since last read an Irving novel, but I remember enjoying them; this book had me wondering why. Irving's style here is pleasant and straightforward, but it's also so full of verbal tics that it quickly becomes wearing. The story is, at its most basic level, simply not credible, and unfortunately many of the intricacies aren't either. Daniel, as an adult, is unpleasantly self-centered, and untroubled by it. Ketchum, the frequently appearing friend, is mainly an ass. Irving seems to see this, though he is careful to present Ketchum from his protagonists' point of view. Nonetheless, I got tired of Ketchum very fast.
The best part of the book is the relationship between Daniel and his father, and happily that's the bulk of the book. But so much of the color is bothersome that the book was more tiring than fun. I recall being uplifted and moved by A Prayer for Owen Meany. This book did neither of those things for me. The style of the writing didn't help. Not only are there verbal tics, but the story constantly jumps around in time, for no apparent reason other than that while the author was writing one thing, he thought of something that happened earlier or later.
Worth reading for those who really like Irving. If you're new to him, start with Owen Meany or The Cider House Rules, not here.