Ah, but that's where you're wrong - it doesn't really do what it was designed to do and it doesn't do it well. It was designed as a quick-and-dirty way to add dynamic content to web pages. I thought that was a great idea, and I've used it in the past for that. I liked the idea so much that I copied it when I made PerlHP, even if that was half a joke (doesn't stop me from using it, though).
However, with every iteration, it moves further and further away from that initial idea, and tries to be a fully-fledged programming language for writing arbitary web apps. But it wasn't designed for this in the first place, and this shows - it's full of kludges, questionable security practices, and half-assed programming constructs. As a general-purpose programming language it is a mess.
And while I think making a programming language that is accessible to non-experts is a laudable goal, PHP is not going about it the right way. Instead of offering the user easy ways to use good practices in code, it almost encourages the inexperienced user to write ugly and insecure code.
http://4-ch.net/code/kareha.pl/1120533289/9 summed this up much better than I could. Where a decent language has simple, secure constructs, PHP requires a mess of conditionals and obscure functions. Not even moderately experienced PHP programmers could really be expected to get this right, never mind all the inexperienced programmers using PHP to do these exact things.
Most larger-scale uses of PHP (that is, more than adding a little bit of dynamic content to an otherwise static HTML page) would be much better served by another language - I like Perl, of course, but Python and Ruby are also far better candidates than PHP will ever be. They all have higher barriers of entry than PHP, but not all that much higher, and the programmer will benefit from having a better idea of what she is actually doing. To repeat myself, I don't oppose the idea of a simple language with a low barrier of entry - it's just that such a langauge should go to much further lengths to protect its user from shooting herself in the foot, something PHP most certainly doesn't do (and which the somewhat more complex language DO).
In the end, I dislike PHP for much the same reasons I dislike Visual Basic. It's a simplified language that lets people write code without really understanding what they are doing, creating a huge base of badly written software, and re-inforcing bad design behaviours in novice programmers world-wide. And by its popularity, it is marginalizing the programming languages that would serve people far better (see how hosting companies without fail will offer PHP, but Perl support is not at all as common, to say nothing of Python or Ruby).
Satisfied?