There is nothing terrible about PHP, and if you like it you should feel free to use it. However,

1. More large sites run on Perl than on PHP. Amazon.com, CitySearch.com, Ticketmaster.com, IMDB.com all run Perl. Yahoo uses some PHP, but they also use Perl, and pretty much everything else.

2. More good programmers use Perl. PHP doesn't have the same culture around things like unit testing, separation of application from interface (with MVC and templates), and reusable code (CPAN) that Perl does.