Unlike many books that focus solely on the birds, Chester talks a lot about his relationship with B and his personal struggles. Specifically, Chester struggles with depression. You really sympathize with Chester and suffer along with him. In the world of bird books, it's a refreshing change from the typical saccharine books about pets.
Some people may dislike his writing style, so it's important to be prepared before investing time in the book. Chester is a bit of a philosopher and the biggest complaint on Amazon is that he uses "big words" when shorter words would suffice. He's not pretentious, though, so I think that once readers dislike the style, they'll look for any way to criticize the book.
I wish he wrote more than this one book, but sadly Chester died in 2007. There is a very detailed article about him here if you're interested.