I love Hornby's writing in general, and I learned why in the jacket flap copy of this book where a New Yorker reviewer called him "the maestro of the male confessional." That's why.
That said, this is not his best effort. Sam unwittingly becomes a 16-year-old father, just like his 32-year-old mother did in her time. The portrayal of the situation is realistic, with Sam spacing out when things get too emotionally tricky. However, the narrative itself invokes skater Tony Hawk and time travel in ways that are amusing for awhile, but ultimately distracting. I found the narrative really dragging when, after Sam has flashed forward to the future, we then arrive at that future and plod through the events again, albeit with a wiser Sam. The time travel felt like a device to show that he had grown rather than an organic component of the story. However, Sam's obsession with that incessant quotation from Tony Hawk's autobiography were convincing, reflecting the power of adolescent obsession.
I'd recommend it for Hornby (and male confessional) fans, but not for the general reader. If you're starting with Hornby, read About a Boy or High Fidelity instead.