As eBay has grown enormously, it has continually added new features, for both buyers and sellers. The complexities of which help drive the need for a book like this. Holden doesn't just confine himself to explaining procedures on the eBay website. He goes into ancillary topics like what the selling of seasonal items might involve, or the finding of wholesalers of items that you might buy from, and then resell on eBay.
While he discusses both buying and selling, you quickly find that the attention is focused on being a heavy seller. When you read elsewhere of people supporting themselves on eBay, it is by being these sellers. So a lot of the utility of the book is in the advice around building up sales, where the mechanics of running auctions is really a lesser detail.
His advice is generally good, with one important caveat. The book never really questions under what circumstances you might not want to sell on eBay. It does not discuss alternatives like Amazon, if you are selling non-collectible items like books, CDs, DVDs and software. eBay charges a listing fee, even if no bids are placed. And currently, some 53% of its auctions end with no bids. So the listing fees can significantly add to your cost, especially since an auction is just for 10 days at most. By contrast, Amazon levies no listing fees. Though if something sells on Amazon, its commission percentage is higher than eBay's. So there are tradeoffs. Plus, in recent years, eBay has repeatedly raised many of its fees. Leading to deep dissatisfaction from many of its largest sellers, who feel that the company is ripping them off.
The book would be of more use to a reader if it broached such topics.