Yikes. I knew PHP had some bad points, I didn't know exactly how many!
This is a good article about why PHP is bad. As someone who wrote PHP professionally for longer than I'd like to admit, I agree with most of the article, even if it is a little hyperbolic at times*. It's worth scanning over the massive list of legitimate problems just to get a visceral sense of how broken PHP really is.
(* The hyperbole is forgivable, though, as programming is such a subtle field that it's difficult to make a good point without taking an extreme position. There are many "Yes, but-" responses one could make, and the author even discusses a few of them.)
PHP: a fractal of bad design - fuzzy notepad