[swivelmaster]

It depends on a lot of factors. I worked at a startup that used PHP and the initial code quality of Product A was godawful because some early hires didn't know how to properly structure their code. Over the next few years, as staff turned over, we were able to clean it up considerably, add a lot of good OO practices, and get to a point where new developers who didn't even have PHP experience could be very productive very quickly.

When we started a Product B about nine months into my time there, the new team wrote new, well-designed code from scratch, and was also very productive very quickly.

PHP lets you easily shoot yourself in the foot, but it also gives you all the tools you need to leave your feet in very good condition, and it's not difficult to do that either.