NuSphere's PhpED is one of the older IDEs around, but it's one of the few that's avoided going astray and diluting itself by supporting every possible language. It's a PHP tool, and this is obvious from the moment you install it.
The tool comes with a sophisticated wizard for checking installation to make sure the debugger and the internal server were correctly configured. I found the simple wizard a welcome break from spending time trying to get the other IDEs to work with the server software installed. It's still possible to use PhpED with a separate version of PHP, but it's not necessary.
Not everything was perfect. The tools generally worked, offering all of the more sophisticated code manipulation features like code folding.
I had some trouble getting the IDE to connect to either MySQL 5.1 or 5.5 because it said I was using an old version of the client software. The forum would let me search, but then it would accuse me of generating automated searches for some reason.
Despite these issues, I found PhpED to be one of the easier tools to use. The user interface was snappy, and the integrated server made it simpler to start projects. PhpED is one of the most pleasant tools in the game.