"What features of PHP do you need/want that JSP doesn't provide?"
I don't know JSP well enough to answer that. My interest in using PHP rather than JSP is two-fold:
1. I know PHP fairly well and I'm confident I can code the PHP (presentation) aspects of the web application I want to put together.
2. Many more companies (ISP) provide support for PHP.
What are the impediments, if any, to using PHP for presentation aspects of web app?