EDIT: refer https://twitter.com/#!/codinghorror/status/18957165652253491... - Jeff's 4 year old response is still valid.
http://me.veekun.com/blog/2012/04/09/php-a-fractal-of-bad-de...
Jeff gets it right - the language is poorly designed, but it hasn't stopped PHP powering many of the biggest most important sites on the internet today. Banging on about the language's flaws [again] is not very interesting. What would be fascinating would be an attempt to understand why PHP remains so dominant despite the well-known flaws.
Seriously - http://stackoverflow.com/questions/tagged/php throws up so many pearls of WTF that you wonder how PHP could possibly be so important. And yet!
Time to stop the PHP bashing. It's like comp.lang.js complaining about the flaws of jQuery (and, indeed, any JS library) and expounding the many and various reasons you should never use a third party library. The reality is: when the keyboard meets the road, stuff has to get done, and these are the tools that seem to work.