To cover the ground this book does in such a relatively short volume there were always going to be limitations. Assumptions are made about backgrounds, this is not a book for complete 'newbies' to the web. A HTML / XHTML / XML primer would be highly beneficial, as well as a rough understanding of what a database is.
However the book walks the reader through evolving code examples brilliantly, development by increments rather than leaps is the methodology. The learning curve is steep but in order to cover the scope it has to be. The samples given get you going very quickly, producing real results from Chapter 2 (introduction to PHP) onwards.
The book uses MySQL 4.0 as its base install, 4.1 installation is a little problematic if the steps in the book are followed to the letter. The book also does all its database maintenance excercises through PHP scripts, good for practice but not very real worldy where an admin tool like PHPMyAdmin would be more likely to be used.
All in all good value for money and a good introduction that will make the reader productive without going anywhere else for information.