This covers the basics you will always need in PHP - array and string manipulation, file access and databases being the most important.
It alerts you to 'gotchas' which can trip you up (best way to search for substrings etc.). It also covers version up to PHP 5.4, given 5.5 is only slightly different it means it's up to date.
The only downsides to this book, are that the author is writing in English as a second language and is sometimes shows, the English isn't really very natural and the MySQL in the title is misleading, it covers many databases and MySQL isn't really a priority.
Worth buying though, the update is worth paying for.