In this article on WebProNews, Andreas Roell praises PHP, nothing several strengths and its flexibility while the fact that it's kept its reliability over time.
PHP has been able to stand its ground as a consistently implemented server-side scripting language. PHP is a general-purpose scripting language that is ideally suited for web developers, and can be easily embedded into HTML.
He mentions the advantage it has of being Open Source as well as flexible enough to run on just about anything out there. PHP can be more cost-efficient than other solutions and, since it is Open Source, you're not left waiting for a company to release their next patch when they feel like it (fix it yourself!). And, of course, what would an article singing the praises of PHP be without a brief mention of its competitor, ASP.